Some 164,000 mostly Rohingya refugees have now crossed into Bangladesh in the last fortnight to escape fighting between militants and Myanmar's military, the United Nations said on Thursday.
The latest figures means more than a quarter of a million Rohingya Muslims have fled Myanmar since fighting first broke out last October, plunging neighbouring Bangladesh into the middle of a major humanitarian catastrophe.
The most recent exodus was sparked by a military crackdown following a series of deadly raids by Rohingya militants on August 25.
A further 87,000 refugees had already fled to Bangladesh between October and August 25.
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.
Despite many living there for generations, they are viewed in Myanmar as illegal immigrants from Bangladesh.
Yet Bangladesh, which by last October already hosted some 400,000 Rohingya who had fled previous episodes of violence, also does not view them as its citizens making them the largest stateless community in the world.
The fighting is the most fierce Myanmar's western Rakhine state has witnessed in years.
The region, Myanmar's poorest state, has been a crucible of communal tensions between Buddhists and Muslims for years.
Myanmar says some 27,000 mainly ethnic Buddhist Rakhine have also fled in the opposite direction since August 25, accusing Rohingya militants of targeting their communities.
Earlier this year United Nations investigators said the Myanmar military's response to the ambushes had unleashed "devastating cruelty" on Rohingya civilians which may amount to ethnic cleansing.
Those flocking into Bangladesh have brought with them harrowing testimony of murder, rape and widespread arson at the hands of Myanmar's army.
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.
On Wednesday Suu Kyi said global sympathy for the Rohingyas was being generated by a "huge iceberg of misinformation".
Myanmar's government has placed the blame for the violence squarely on the militants, saying they are setting fire to their own homes.
In updated figures released by the authorities on Thursday, Myanmar said 6,600 Rohingya homes and 201 non-Muslim homes had been burned to the ground since August 25.
They added some 30 civilians had been killed -- seven Rohingyas, seven Hindus and 16 Rakhine Buddhists -- in the fighting.
Myanmar's army has previously said it has killed around 430 Rohingya militants.