Activist groups have accused the Burmese army of burning down villages and shooting Rohingya Muslim civilians as part of a crackdown on insurgents in Rakhine state.
Violence has driven thousands of Rohingya Muslims fleeing towards Bangladesh for safety, along with a smaller exodus of ethnic Rakhine Buddhists, where they face growing danger of sickness and attempts by the Bangladesh authorities to send them home.
The Burmese government has blamed Rohingya insurgents for the violence, including the arson.
Laura Haigh, Amnesty International's Burma researcher, said reports of villages being burned were "deeply disturbing."
"While the Myanmar authorities have the duty to investigate criminal attacks on security force posts, they must refrain from violence, and ensure that they are making every effort to distinguish between suspected militants and ordinary people," she said, using an alternative name for Burma.
"This cannot lead to a repeat of last year’s vicious military reprisals responding to a similar attack, when security forces tortured, killed and raped Rohingya people and burned down whole villages."
Insurgents launched coordinated attacks last week against police patrols, with the government giving an official death toll of 96, although the actual number is likely to be higher.
Both the government, in official statements, and its critics, in posts on social media often accompanied by video clips, said there was widespread burning of buildings and even whole neighbourhoods in Maungdaw township in northern Rakhine.
"Extremist terrorists blew out improvised bombs, set fire the villages and attacked the police outposts in Region-2 of Maungtaw yesterday from the morning to afternoon," an English-language statement issued by the Information Ministry said.
Arakan Times, an online news website serving the Rohingya community, said Burmese troops and border guard police burned down 1,000 homes in actions beginning Saturday and continuing on Monday.
Both sides' claims are difficult to verify, because the government denies most journalists access to the area.
New York-based Human Rights Watch said satellite photos appear to show widespread burning in 10 areas of northern Rakhine.
While the causes of the fires could not be ascertained, it noted that it "compared the locations of these fires with witness statements it has collected and media reports, and found a correlation with some reported incidents where residences have allegedly been deliberately burned."
The group urged the government to "grant access to independent monitors to determine the sources of fires and assess allegations of human rights violations."
A Rohingya insurgent group, the Arakan Rohingya Salvation Army, or ARSA, took responsibility for Thursday night's attacks on more than 25 locations, saying they were in defence of Rohingya communities that had been brutalised by government forces. They vowed to continue to defend the communities.
The treatment of around 1.1 million Muslim Rohingya in Burma has become the biggest challenge for national leader Aung San Suu Kyi, who has been accused by Western critics of not speaking out on behalf of the long-persecuted minority.
The Rohingya have faced severe discrimination and were the targets of violence in 2012 that killed hundreds and drove about 140,000 people — predominantly Rohingya — from their homes to camps for the internally displaced, where most remain.
The government refuses to recognise Rohingya as a legitimate native ethnic minority and most Rohingya are denied citizenship and its rights.
Additional reporting by agencies
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