Myanmar has waged "a campaign of ethnic cleansing" against Rohingya Muslims, a top rights watchdog said Monday, citing evidence of mass graves and forced displacement affecting tens of thousands.
The Rohingya, who are denied citizenship by the country also known as Burma, have faced crimes against humanity including murder, persecution, deportation and forced transfer, New York-based Human Rights Watch said.
Myanmar officials, community leaders and Buddhist monks organised and encouraged mobs, backed by state security forces, to conduct coordinated attacks on Muslim villages in October in the western state of Rakhine, HRW said.
"The Burmese government engaged in a campaign of ethnic cleansing against the Rohingya that continues today through the denial of aid and restrictions on movement," said HRW deputy Asia director Phil Robertson.
The report was released on the same day that the European Union lifted all remaining sanctions against Myanmar, except an arms embargo, in a move that Robertson said was "premature and unfortunate" and would diminish the EU's leverage with the regime.
He called on all international donors, including the United States, to step up pressure on Myanmar to promote democratic change in the former pariah state, which ended decades of military rule in 2011.
The situation in Rakhine "if allowed to fester will ultimately threaten the larger effort towards reforms", Robertson told reporters in Bangkok.
Myanmar presidential spokesman Ye Htut accused HRW of timing its report to coincide with the EU sanctions decision.
"The government will not pay attention to such a one-sided report," he said in comments posted on his Facebook page.
He said that the authorities would instead await the findings of an official commission set up to investigate the violence, whose release has been delayed several times.
HRW noted that while ethnic cleansing was not a formal legal term, it was generally defined as a policy by one ethnic or religious group to remove another group from certain areas through violence and terror.
In Rakhine, more than 125,000 Rohingya and other Muslims have been forcibly displaced, denied access to humanitarian aid and are unable to return home, the group said.
According to government figures cited by HRW, 211 people have died in two outbreaks of Buddhist-Muslim violence in Rakhine since June 2012, but the rights monitor said it believed the real figure was much higher.
In a report based on more than 100 interviews, it said that it had uncovered evidence of four mass graves in Rakhine.
In one episode in June, according to HRW, a government truck dumped 18 naked and half-clothed bodies near a camp for displaced Rohingya, describing it as an attempt to scare them into leaving.
In the deadliest incident, according to the rights watchdog, about 50-70 Rohingya, including 28 children, were reportedly killed in a village after police and soldiers disarmed them and failed to protect them from a mob.
Myanmar views its population of roughly 800,000 Rohingya as illegal Bangladeshi immigrants. Thousands have fled Myanmar since June on rickety boats, mostly believed to be heading for Malaysia after Bangladesh refused them entry.
Other Muslims were also targeted in violence last month in central Myanmar, where at least 43 people were killed.
The BBC on Monday released footage which appeared to show police standing by as Buddhist rioters, including monks, attacked Muslims in the town of Meiktila in March.
The British broadcaster said in one case police looked on as a severely burned man lay on the ground unaided.
Robertson said that "impunity" for abuses in Rakhine had encouraged extremists in other parts of the country.
"The central government has taken no action to punish those responsible or reverse the ethnic cleansing of the forcibly displaced Muslims," he said.
Human Rights Watch and other campaign groups have urged democracy leader Aung San Suu Kyi to speak out more forcefully on the plight of Myanmar's minorities, in the buildup to general elections due to take place in 2015.
Last week in Tokyo, the Nobel Peace Prize winner said she felt "sad" at the anti-Muslim bloodshed and urged respect for the "rule of law".
Late Monday, a US state department spokesman, Patrick Ventrell, said: "We continue to engage vigorously with... the Burmese government on this issue, and we'll continue to urge at every step and with all audiences... the importance of lasting peace and the end of any sectarian or communal violence in Burma."