( CNN ) -- Chinese authorities have made dozens of arrests following a deadly clash between Han Chinese and ethnic Uighurs in the country 's remote northwest , a U.S.-based Uighur leader said Wednesday . China 's state news agency Xinhua said 12 people were killed in rioting near the northwestern city of Kashgar , including two shot and killed by police during Tuesday 's melee . Xinhua said the trouble began when a group of knife-wielding assailants attacked people in a market . But Omer Kanat , vice president of the World Uighur Congress , put the toll at 16 , including seven members of China 's security forces . `` We have heard different accounts . We do n't know exactly what happened , '' Kanat said . But local residents have told the group that the rioting began with a dispute between Uighur youth and Han Chinese settlers in a market , he said . `` The Chinese authorities already launched a crackdown and an arrest campaign after this , and according to our information , 80 people are arrested , '' he said . `` They are now looking for the people involved in this incident . '' Neither account could be independently verified . Uighurs are predominantly Muslim ethnic Turks who are linguistically , culturally and religiously distinct from China 's majority Han population . Chinese authorities have blamed Islamic militants of Uighur descent for previous outbreaks of violence in Xinjiang province , where Uighur-Han Chinese rioting in July 2009 left nearly 200 people dead and 1,700 injured . The massive security clampdown in the wake of the violence has angered many Uighurs , who make up more than half of the 9 million people that live in the far western region of China . `` This crackdown is ongoing , '' Kanat said . `` They restricted everything , every movement of the Uighurs . So the people are frustrated , and there is no way to express your grievances . Some individuals resort to violence , unfortunately . '' Tuesday 's rioting coincides with the opening of a new 3.64 billion yuan ( $ 579 million ) highway linking Kashgar to Yecheng , which lies 155 miles ( 258 km ) to the south . Beijing says militant Uighur groups linked to the East Turkistan Islamic Movement , a separatist organization it says operates from neighboring Afghanistan and Pakistan , have been fomenting trouble in the region . In December , Chinese authorities killed seven Uighurs in a bid to free two hostages kidnapped in the rural county of Pishan , near Yecheng -- an incident the Stockholm-based World Uighur Congress disputes . The WUC said the deaths occurred when police opened fire on a demonstration outside a police bureau where Uighurs were protesting a recent security crackdown in Hotan city . And authorities in Xinjiang said last month they plan to recruit 8,000 extra police officers as China strengthens security in the run-up to a major leadership transition later this year . Kanat said additional police `` will not work , and there will be more violence . '' `` But they are not trying to prevent that violence by listening to the grievances of the people , '' he said . `` They do n't want to listen to them . They just want to suppress all dissent by force . '' CNN 's Peter Shadbolt contributed to this report .
NEW : The World Uighur Congress says 16 people died in Tuesday 's rioting . China 's Xinhua news agency put the death toll at 12 , including two killed by police . Beijing has blamed militants of Uighur descent for outbreaks of violence in Xinjiang in recent years . Comment: