Myanmar government has evacuated at least 4,000 non-Muslim villagers amid ongoing clashes in northwestern Rakhine state, the government said, while thousands of Rohingya Muslims fled across the border to Bangladesh.

The death toll from the violence that erupted on Friday with coordinated attacks by Rohingya insurgents has climbed to 98, including some 80 insurgents and 12 members of the security forces, the government said. The clashes, the worst since at least October, have prompted the government to evacuate staff and thousands of non-Muslim villagers from the area.

Fighting involving the military and hundreds of Rohingya across northwestern Rakhine continued on Saturday with the fiercest clashes taking place on the outskirts of the major town of Maungdaw, according to residents and the government.

The attacks marked a dramatic escalation of a conflict that has simmered in the region since last October, when a similar but much smaller Rohingya attack prompted a brutal military operation beset by allegations of serious human rights abuses.

The treatment of approximately 1.1 million Muslim Rohingya in mainly Buddhist Myanmar has emerged as the biggest challenge for national leader Aung San Suu Kyi. Suu Kyi on Friday condemned the raids in which insurgents wielding guns, sticks and homemade bombs assaulted 30 police stations and an army base.

The Nobel Peace Prize laureate has been accused by some Western critics of not speaking out for the long-persecuted Muslim minority, and of defending the army's counteroffensive after the October attacks.

Win Myat Aye, Myanmar's minister for social welfare, relief and resettlement, told Reuters late on Saturday that 4,000 "ethnic villagers" who had fled their villages had been evacuated, referring to non-Muslim residents of the area.

The ministry is arranging facilities for non-Muslims in places including Buddhist monasteries, government offices and local police stations in major cities.

"We are providing food to the people cooperating with the state government and local authorities," said Win Myat Aye.

He was unable to describe the government's plans to help Rohingya civilians.

"It is very difficult to say - this is a conflict situation so it is very difficult to say who is right or wrong," he said.

Panic-stricken Rakhine residents in ethnically mixed or non-Muslim towns have readied knives and sticks to defend themselves. Many were stranded in their villages located in Muslim-majority areas as clashes continued and some roads had been mined, residents said.

"The clashes continued all day yesterday on the main road, there are a lot of landmines. I don't think local authorities have enough food for all the people. The price of commodities is rising day by day," a local journalist from Maungdaw town said on Sunday.

Bracing for more violence, thousands of Rohingya - mostly women and children - were trying to forge the Naf river separating Myanmar and Bangladesh and the land border as gunfire could be heard from the Myanmar side, Bangladesh border guards said.

Around 2,000 people have been able to cross into Bangladesh since Friday, according to estimates by Rohingya refugees living in the makeshift camps on the Bangladeshi side of the border.

Bangladesh's foreign ministry said it was concerned that thousands of "unarmed Myanmar nationals" had assembled near the border to enter the country.

Rohingya have been fleeing Myanmar to Bangladesh since the early 1990s and there are now around 400,000 in the country, where they are a source of tension between the two nations who both regard them as the other country's citizens. (Additional reporting by Shoon Naing in YANGON and Krishna N. Das in NEW DELHI; Writing by Antoni Slodkowski; Editing by Lincoln Feast)