UN investigators have for the first time declared the violence against Rohingya Muslims in northern Myanmar to be a campaign of genocide.

In a damning final report from their fact-finding mission, observers said Myanmar’s commander-in-chief and five other named generals should face prosecution for acting with “genocidal intent”, crimes against humanity and war crimes.

It is by far the strongest condemnation yet from the international community for a widespread military crackdown by the authorities in Rakhine state, which began on 25 August last year. The army said it had been responding to violent attacks by a Rohingya Muslim militant group.

But hundreds of Rohingya in exile spoke to the UN’s fact-finding team, working under the mandate of the Human Rights Council, to describe the burning of entire villages, gang rape of women and mass extrajudicial killings of civilians.

The violence sparked the exodus of more than 700,000 Rohingya to neighbouring Bangladesh, where they have been given shelter and support by the government and NGOs but still lack basic rights and citizenship.

Marzuki Darusman, chairman of the investigative team, said Myanmar’s military commander Min Aung Hlaing should step down in the wake of the report.

Rohingya crisis one year on – Myanmar camps in pictures Show all 30 1 /30 Rohingya crisis one year on – Myanmar camps in pictures Rohingya crisis one year on – Myanmar camps in pictures Rohingya women and children wait in line for a food distribution of super cereal at Action Against Hunger Getty Images Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees gather near the fence in the "no man's land" zone between Myanmar and Bangladesh border AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya women cry as they shout slogans during a protest rally to commemorate the first anniversary of Myanmar army's crackdown AP Rohingya crisis one year on – Myanmar camps in pictures A Rohingya Muslim child holding an umbrella while under the rain AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees cry as they pray during a gathering to commemorate the first anniversary of Myanmar army's crackdown which lead to a mass exodus of Rohingya Muslims to Bangladesh AP Rohingya crisis one year on – Myanmar camps in pictures Police stand near the checkpoint at the Shwe Zar village in Maungdaw township, Rakhine State, western Myanmar EPA Rohingya crisis one year on – Myanmar camps in pictures A group of Rohingya refugee children stand at a makeshift camp EPA Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugee Juhara, whose name has been changed to protect her identity, poses for a portrait at the Kutapalong refugee camp near Cox's Bazar in southern Bangladesh. Juhara passes her days carting water with difficulty to thirsty bricklayers working in a bustling corner of Cox's Bazar. She has just one hand - the other was cleaved off in a raid on her village after the August 25 clampdown started last year. Her husband and parents were killed. The 40-year-old said she ran for her life but was hunted down and savagely attacked AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees walk on a road along a makeshift camp in Kutubpalang EPA Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees are seen outside of their makeshift tent in the Kutupalong camp in Cox's Bazar Reuters Rohingya crisis one year on – Myanmar camps in pictures Thousands of Rohingya refugees staged protests for "justice" on August 25 on the first anniversary of a Myanmar military crackdown that forced them to flee to camps in Bangladesh AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures A Rohingya refugee child looks through a window at a makeshift camp in Teknuf EPA Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugee women hold placards as they take part in a protest at the Kutupalong refugee camp Reuters Rohingya crisis one year on – Myanmar camps in pictures A young Rohingya boy waits in line for a food Getty Images Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees shout slogans during a protest march AFP/Getty Images Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugee girl with other children at a makeshift camp in Teknuf in Cox's Bazar EPA Rohingya crisis one year on – Myanmar camps in pictures Rohingya women protest on the first anniversary of the Rohingya crisis Getty Images Rohingya crisis one year on – Myanmar camps in pictures Rohingya women and children receive super cereal at Action Against Hunger Getty Images Rohingya crisis one year on – Myanmar camps in pictures Rohingya girls share a laugh in Kutupalong, the largest refugee camp housing the Rohingya Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees gather near the fence in the "no man's land" zone between Myanmar and Bangladesh border AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees attend a ceremony organised to remember the first anniversary of a military crackdown that prompted a massive exodus of people from Myanmar to Bangladesh AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rashida Begum, a Rohingya refugee woman walks on the Kutupalong camp in Cox's Bazar Reuters Rohingya crisis one year on – Myanmar camps in pictures A Rohingya refugee bursts into tears as she shouts slogans during a protest march AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugee baby Nur Sadek two years old undergoing treatment at a Medecins Sans Frontieres (MSF) hospital in Teknuf in Cox's Bazar EPA Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees protest Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees perform prayers AFP/Getty Rohingya crisis one year on – Myanmar camps in pictures Rashida Begum, a Rohingya refugee woman bathes her son in the Kutupalong camp Reuters Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees protest Getty Rohingya crisis one year on – Myanmar camps in pictures Rohingya refugees walk on a muddy road EPA Rohingya crisis one year on – Myanmar camps in pictures Rohingya women and children wait in line for a food distribution of super cereal at Action Against Hunger Getty

“The only way forward is to call for his resignation and stepping down immediately,” he told a news conference in Geneva.

In its report, which also relied on satellite footage and other corroborating information, the UN team cited a “conservative” estimate that some 10,000 people were killed in the violence.

Myanmar’s government refused the UN’s team access to the affected region, and the report released on Monday decried a lack of cooperation or even response from the government, which received an early copy of the report.

In dismissing the Myanmar army’s justification for the crackdown, it read: “Military necessity would never justify killing indiscriminately, gang raping women, assaulting children, and burning entire villages. The Tatmadaw’s [the military’s] tactics are consistently and grossly disproportionate to actual security threats, especially in Rakhine state, but also in northern Myanmar.

“They are shocking for the level of denial, normalcy and impunity that is attached to them. The Tatmadaw’s contempt for human life, integrity and freedom, and for international law generally, should be a cause of concern for the entire population.”

The investigators said the situation in Myanmar should be referred to the International Criminal Court, and if not, to a special tribunal. Myanmar is not a treaty member of the ICC – but it is one of the 47 member states of the Human Rights Council, meaning Monday’s report will carry greater weight than any that have come previously.

In naming six generals as prime candidates for prosecution at the ICC, the UN’s report admits that the civilian government in Myanmar has little power to control the country’s military.

Nonetheless, it includes damning words for the civilian government of Nobel Peace Prize laureate and Oxford graduate Aung San Suu Kyi, saying that “through their acts and omissions, the civilian authorities have contributed to the commission of atrocity crimes”.

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“State Counsellor Suu Kyi has not used her de facto position as head of government, nor her moral authority, to stem or prevent the unfolding events in Rakhine State,” it says.

The report does not suggest that the crisis, which began a year ago, was a surprise – rather, it refers to a “catastrophe looming for decades” as a result of the “severe, systemic and institutionalised oppression from birth to death” of the Rohingya people.

The UN mission found the violence of August 2017 was underpinned by numerous examples of hate speech and incitement, including when in November 2012 a leading Rakhine political party cited Hitler, arguing that “inhuman acts” were sometimes necessary to “maintain a race”.

The UN’s human rights agency said the report relied on 875 in-depth interviews with victims and eyewitnesses as well as satellite imagery and authenticated documents, photographs and videos. The team will next present a fuller report, with analysis of the next possible legal steps, to the Human Rights Council on 18 September.

Mark Field, the UK foreign office minister, said he welcomed the UN mission’s work and said Britain believes “the gravity of the report warrants the attention of both the UN Human Rights Council and the UN Security Council”.

And Michael McGrath of Save the Children, one of the leading charities working to support Rohingya refugees, said it was time “[for] the UN Security Council to refer Myanmar to the International Criminal Court without delay”.