Five Rohingya villagers whose distraught relatives say they were shot dead by the Myanmar military were buried Thursday in Bangladesh at a mass funeral attended by hundreds of people after their bodies were carried across the border.

The relatives said the victims had been killed by the Myanmar military on Wednesday, a claim that could not be independently confirmed but tallies with multiple accounts of killings in Rohingya villages.

Their bodies were brought across the Naf river on a boat, landing on a remote stretch where thousands of Rohingya refugees have been streaming into Bangladesh over the last fortnight.

Sufia Begum, an elderly Rohingya woman aboard, said she had relatives among the dead.

"They were all killed," she wept, pointing to a lifeless man covered in plastic sheeting and another corpse wrapped in cloth.

They were buried on Thursday in a Muslim graveyard along with a sixth man who died of unknown causes.

One victim, identified by survivors as the imam of their village mosque in Myanmar, had sustained a gunshot wound to the head.

"Five of them had bullet wounds," Chailau Marma, deputy police chief of Cox's Bazar, which borders Myanmar, told AFP.

"Relatives of the deceased carried the bodies into Bangladesh after they failed to bury them in Myanmar. They all died yesterday."

Myanmar's more than one million Rohingya are denied citizenship and face severe restrictions in the majority Buddhist country, which has come under increased criticism over its apartheid-like treatment of the Muslim minority.

UN investigators have said a military crackdown that followed ambushes by Rohingya militants in October last year has unleashed "devastating cruelty" on civilians which may amount to ethnic cleansing.

On Thursday the UN said 164,000 refugees have now crossed into Bangladesh in the last fortnight to escape fighting between militants and Myanmar's military.

The fighting is the fiercest Myanmar's western Rakhine state has witnessed in years.

Columns of Rohingya civilians arrived steadily throughout Wednesday from the jungles along the border, carrying infants, chickens and their belongings bundled in sacks.

Long queues formed to cross a collapsed bridge over a marshy river, with elderly civilians with canes and infants being carried across the impasse.

Many have brought allegations of homes being torched and villagers shot and hacked to death by Myanmar troops.

Myanmar's government, led by Nobel peace prize laureate Aung San Suu Kyi, has rejected allegations of atrocities, accusing the international media, NGOs and the UN of fabrications.

Marium Begum, who crossed by river into Bangladesh on Wednesday, said soldiers had opened fire as she and her family tried to flee their village.

"They shot over our heads. We submerged ourselves underwater. The children swallowed a lot of water," she told AFP.

"There were many of them. They had long machetes."

Bangladesh border guards also allowed a Rohingya couple to be buried in Bangladesh after they were shot dead and the wife gang-raped when they went back into Myanmar to retrieve their belongings, commander Manzurul Hasan Khan, told AFP.