The United Nations says over 40 Muslims were killed when a Buddhist mob stormed a village in an isolated corner of western Myanmar last week, hunting down residents with knives and machetes, the UN said. .

The UN High Commissioner for Human Rights, Navi Pillay, said on Thursday she had received credible information that eight Rohingya Muslim men were attacked and killed in Du Chee Yar Tan village by local Rakhine on January 9, followed by a clash in the same village the following week that the UN believes killed at least 40 Rohingya Muslim men, women and children, bringing the total to at least 48.

"I deplore the loss of life in Du Chee Yar Tan 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.

The second clash, on January 13, followed the reported kidnapping and killing of a police sergeant by Rohingya residents, according to witnesses and rights groups.

There needs to be accountability for this wave of horrific violence ... but mass arrests of Muslim men and boys are not the way. Matthew Smith, Executive Director, Fortify Right

Myanmar's government has denied reports of a massacre. Presidential spokesman, Ye Htut, said on Thursday that he "strongly objects" to the UN claims, calling them "totally wrong."

The incident in Du Char Yar Tan, a village in Northern Rakhine state, appears to be the deadliest in a year, and would bring the total number killed nationwide in sectarian violence to more than 280, most of them Muslims.

Another 250,000 people have fled their homes. Northern Rakhine is home to 80 percent of the country's 1 million Muslim Rohingya population, and is off-limits to foreign journalists. Access for humanitarian aid workers is severely restricted.

An independent Thailand-based rights group, Fortify Rights, also said on Thursday that more than 40 were killed.

Government denials

Security forces surrounded Du Char Yar Tan on January 14 after Rohingya Muslim residents allegedly abducted and killed a police sergeant, according to residents who spoke on condition of anonymity because they feared reprisals.

Worried about retaliatory attacks, most of the men fled, and soldiers and police did nothing to stop a Buddhist mob that entered the village with knives and guns, attacking women, children and others left behind, they said.

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.

There are around 1 million Rohingya in Myanmar. The UN has called them one of the most persecuted minorities in the world.