The United Nations warned on Friday that escalating fighting in conflict-torn Myanmar's Rakhine State had forced around 45,000 minority Rohingya to flee, amid allegations of killings and burnings of property.

"Tens of thousands of civilians have been displaced in recent days by the fighting in Buthidaung and Maungdaw townships," UN rights office spokeswoman Elizabeth Throssell told reporters in Geneva.

"An estimated 45,000 Rohingya have reportedly fled to an area on the Naf River near the border with Bangladesh, seeking protection," she said.

Clashes have rocked Rakhine since the Arakan Army (AA) attacked forces of the ruling junta in November, ending a ceasefire that had largely held since a military coup in 2021.

The AA says it is fighting for more autonomy for the ethnic Rakhine population in the state, which is also home to around 600,000 members of the persecuted Rohingya Muslim minority.

Hundreds of thousands of Rohingya fled Rakhine in 2017 during a crackdown by the military that is now the subject of a United Nations genocide court case.

"Over a million Rohingya are already in Bangladesh, having fled past purges," Throssell pointed out.

UN rights chief Volker Turk was urging Bangladesh and other countries "to provide effective protection to those seeking it, in line with international law, and to ensure international solidarity with Bangladesh in hosting Rohingya refugees in Myanmar", she said.

Throssell warned of "clear and present risks of a serious expansion of violence" in Rakhine.

She pointed to the beginning of a battle for Maungdaw town, where the military has outposts and where a large Rohingya community lives.

"In this appalling situation, civilians are once more victimised, killed, their properties destroyed and looted, their demands for safety and security ignored," she said.

"They are again forced to flee their homes in a recurring nightmare of suffering."