YANGON, Myanmar (AP) -- At least 48 Muslims were killed when Buddhist mobs attacked a village in an isolated corner of western Myanmar earlier this month, the United Nations said Thursday, calling on the government to carry out a swift, impartial investigation and to hold those responsible accountable.
Presidential spokesman Ye Htut, who has vehemently denied reports of a massacre, said he "strongly objects" to the U.N. claims.
The facts and figures, he said, are "totally wrong."
Myanmar, a predominantly Buddhist nation of 60 million people, has been grappling with sectarian violence since June 2012.
The incident in Du Chee Yar Tan, a village in Northern Rakhine state, appears to be the deadliest in a year, and would bring the total number killed nationwide to more than 280, most of them Muslims. Another 250,000 people have fled their homes.
Northern Rakhine -- home to 80 percent of the country's 1 million long-persecuted Muslim Rohingya population -- runs along the Bay of Bengal and is cut off from the rest of the country by a mountain range. It is off-limits to foreign journalists and humanitarian aid workers have limited access, adding to the difficulties of confirming details about the violence, which flared more than a week ago.
But evidence of a massacre, first reported by The Associated Press, has been steadily mounting, with injured victims
The U.N. High Commissioner for Human Rights, Navi Pillay, said she had received credible information that eight Rohingya Muslim men were attacked and killed in Du Chee Yar Tan village by local Rakhine on Jan 9. This was followed by a clash on Jan. 13 in the same village, following the reported kidnapping and killing of a police sergeant by Rohingya residents, according to witnesses and rights groups.
That triggered a security crackdown.
Most Rohingya men and boys -- who typically flee when soldiers and police are thought to be approaching, because it is they who usually bear the brunt of abuses -- fled the village in fear, leaving behind mostly women and children. Police did nothing to stop revenge-seeking a Buddhist mob that entered later that night with knives, sticks and swords, witnesses and rights groups said.
Pillay said the U.N. believes at least 40 Rohingya Muslim men, women and children were killed, bringing the total to at least 48.
"I deplore the loss of life ... and call on the authorities to carry out a full, prompt and impartial investigation and ensure that victims and their families receive justice," she said. "By responding to these incidents quickly and decisively, the government has an opportunity to show transparency and accountability, which will strengthen democracy and the rule of law in Myanmar."
The village has been emptied and sealed off since the massacre.
The humanitarian aid group, Medicins san Frontiers, or Doctors Without Borders, which has several clinics in the area, said it has treated at least 22 patients, including several wounded, who are believed to be victims of the violence.
"MSF continues to be concerned by reports that there may be unmet medical needs among the affected population and stands ready to support local health authorities in providing medical care to those in need," the group said in a statement.
Matthew Smith, executive director of the Thailand-based rights group, Fortify Rights, called on the government to give humanitarian workers, independent observers and journalists unfettered access to the area. He said hundreds are still in hiding and may need help.
He also called for an end to mass arrests, saying in the hours that followed the killings, riot police started rounding up all male Rohingya, including children over the age of 10, in surrounding areas.
"These arbitrary detentions broaden the scope of the human rights violations in the area and should be immediately brought to an end," Smith said. "There needs to be accountability for this wave of horrific violence ... but mass arrests of Muslim men and boys are not the way."
The Myanmar government has repeatedly denied that any violence took place in the area, apart from the death of the police sergeant and an alleged attack by Rohingya Muslims on police. Statements have appeared almost daily in the state-run media and government websites.
A statement published on the Ministry of Information website on Thursday said Chief Minister of Rakhine state Hla Maung Tin visited the area on Wednesday and told people about "false news published and aired by foreign media that children and women were killed in the violence."
Officials with the U.N. accompanied the government delegation, but did not comment on that trip.
There are around 1 million Rohingya in Myanmar. The United Nations has called them one of the most persecuted minorities in the world.
Some of the Rohingya are descended from families that have been there for generations. Others arrived more recently from neighboring Bangladesh. All have been denied citizenship, rendering them stateless.
For decades, they have been unable to travel freely, practice their religion, or work as teachers or doctors. They need special approval to marry and are the only people in the country barred from having more than two children.
Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.