( CNN ) -- At least 40 members of a religious minority in Myanmar were killed by security forces and Buddhists in the western village of Du Char Yar Tan last week , a human rights group said . Fortify Rights , a group based in Southeast Asia , claims the attacks against the Rohingya Muslims were carried out after the suspected killing of a police officer , who is still missing . Most of dead were women and children , the group said . But the government denies the killings , and Myanmar 's deputy minister of information told reporters that the news outlets reporting them are `` wholly and totally wrong . '' In a statement , the government outlined the details of an incident that led to the missing police officer at the center of the latest clashes . It apparently started January 13 when a police patrol led by the missing officer encountered a group of men described in the report as Bengalis `` sitting around a fire in front of shops . '' The group apparently started throwing stones at the patrol and was joined shortly after by about 100 villagers with knives and sticks , according to the report . The officers fled , except for police Sgt . Aung Kyaw Thein , who has been missing since . Riot police have moved into the village , and journalists and human rights activists have been denied access , according to Fortify Rights . `` When the police went into the village to find the missing police , almost all the men had fled , leaving women , children and old people , '' a police spokesman told CNN . He said there are so many security forces now looking for the missing police officer that violence between Muslims and Buddhists is no longer possible . Valerie Amos , United Nations under-secretary-general for humanitarian affairs , warned of `` alarming levels of violence , including the killing of many civilians and a policeman . '' She called on Myanmar 's government to launch an impartial investigation into the claims . The U.N. calls the Rohingya Muslims one of the most persecuted populations in the world , and 3,500 of them live in the village of Du Char Yar Tan . They 've been the frequent targets of violence by Buddhists , who are the majority in Myanmar . U.S. President Barack Obama urged Myanmar 's President Thein Sein during a visit to the White House last year to respect the rights of the Rohingya minority .
Many Muslims in Myanmar were killed by security forces , Buddhists , rights group says . U.N. official warns of alarming reports of violence and calls for an investigation . Government says reports of violence are false but confirms clashes with police . Rohingya Muslims are a minority in Myanmar and have been attacked before .