About 164,000 Rohingya have flooded into Bangladesh since violence erupted in Burma on August 25, the UN's refugee agency said.
The updated figure came as journalists reported new fires burning in a Burmese village abandoned by Rohingya, with pages ripped from Islamic texts left on the ground, intensifying doubts about government claims that members of the persecuted minority had been destroying their own homes.
About two dozen journalists saw the fires in Gawdu Zara village in northern Rakhine state on a government-controlled trip.
It comes after Rohingya insurgents attacked police outposts including in Gawdu Zara, the UNHCR said.
The Burmese military has said nearly 400 people, most they described as insurgents, had died in clashes and that troops were conducting "clearance operations". It has blamed insurgents for setting the villages on fire, without offering proof.
The Rohingya who have fled Burma described large-scale violence perpetrated by Burmese troops and Buddhist mobs - setting fire to their homes, spraying bullets indiscriminately, stabbing civilians and ordering them to abandon their homes or be killed.
On the Burmese side of the border, reporters saw no Rohingya in any of the five destroyed villages they were allowed to tour on Thursday, making it unlikely they could have been responsible for the fires.
One ethnic Rakhine villager who emerged from the smoke said police and Rakhine Buddhists had set the fires.
No police were seen in the village beyond those who were accompanying the journalists, but about 10 Rakhine men with machetes were seen.
Among the buildings on fire was a madrassa, an Islamic school. Copies of books with texts from the Koran, Islam's holy book, were torn up and thrown outside.
Another village the journalists visited, Ah Lel Than Kyaw, was blackened, obliterated and deserted.
Local police officer Aung Kyaw Moe said 18 people were killed in the village when the violence began last month. "From our side, there was one immigration officer dead, and we found 17 dead bodies from the enemy side," he said.
He said the fires were set on August 25, though some of them continued to burn. Virtually all buildings in the village seen by journalists had been burned, along with cars, motorbikes and bicycles that fleeing villagers left behind. A mosque was also damaged.
Burning Rohingya homes can make it less likely that they return. Tens of thousands were driven from their homes in another wave of violence in 2012. Many are now confined to camps, while the land they once held is either vacant or occupied by Buddhist squatters.
Burma refers to Rohingya as Bengalis, contending they migrated illegally from Bangladesh, though many Rohingya families have lived in Burma for generations.
Burmese leader Aung San Suu Kyi has dismissed the Rohingya crisis as a misinformation campaign.
According to her office, she said such misinformation helps promote the interests of "terrorists", a reference to the Rohingya insurgents who attacked security posts on August 25.
The crisis response director for Amnesty International called Ms Suu Kyi's response "unconscionable."
On Thursday, Ms Suu Kyi told reporters her government was working to improve security and livelihoods for Rohingya, but that it is "a little unreasonable to expect us to resolve everything in 18 months" since her administration took office.
With Rohingya fleeing by the thousands daily across the border, pushing existing camps in Bangladesh to the brink, the government in Dhaka pledged to build at least one more.
The International Organisation for Migration has pleaded for 18 million US dollars (£13 million) in foreign aid to help feed and shelter tens of thousands now packed into makeshift settlements or stranded in a no man's land between the two countries' borders.