Burmese soldiers have again fired shots as they attempt to disperse thousands of anti-government protesters in the main city, Rangoon.
There are now more ordinary people on the streets
Witnesses said it was not clear whether bullets were fired into the crowd or above heads. At least one person - a Japanese man - has been killed.
The military have been broadcasting warnings that the protesters should go home or face "serious action".
World leaders have renewed their calls for an end to the violence.
The fresh protests follow reports of overnight raids on six monasteries.
According to witnesses, soldiers smashed windows and doors and beat the sleeping monks. Some escaped but hundreds of monks were taken away in military trucks.
Two members of the National League for Democracy, the party led by opposition leader Aung San Suu Kyi, were also arrested overnight.
Britain's ambassador to Burma, Mark Canning, told the BBC he believed Ms Suu Kyi was still under house arrest at her home, amid reports that she had been sent to Rangoon's Insein prison.
"We still think that because there is a very, very heavy guard presence on University Avenue that she must be in her house halfway down that street," he said.
Around midday, thousands of people poured onto the streets of Rangoon in an apparently spontaneous show of defiance. They began singing nationalist songs and hurling abuse at the soldiers driving by in trucks.
The soldiers responded with gunfire.
"They have shot several times into the crowd," one witness told the BBC.
"One person was injured... they used tear gas... Now the injured person is carried off into a car to be taken to hospital... they [the soldiers] are using force on us."
There are fewer monks on the streets - since so many were arrested - and there are large numbers of ordinary people instead, reports the BBC's Chris Hogg in Bangkok.
It means the military may have fewer qualms about firing on the crowd, he reports. Monks are held in high esteem in Buddhist Burma.
Japan's foreign ministry said it was working to identify a man found dead in Rangoon carrying a Japanese passport.
The Japanese news agency APF News said the dead man was a video journalist who had been in Burma for the agency since Tuesday.
The British embassy has told the BBC that four people were shot in the north of Rangoon.
Four army vehicles were surrounded and the soldiers opened fire in response, the embassy said. Earlier reports said the victims had been killed, but the embassy later said their condition was not known.
A hotel in which foreign journalists have been staying in Rangoon has been surrounded and ransacked, our correspondent reports.
Security forces have set up barbed wire barricades around the Shwedagon Pagoda and Rangoon city hall, two of the focal points for the demonstrations.
On Wednesday, five people were reported to have been killed when police broke up protests. The military government has confirmed one death.
There are no indications yet that the military government is ready to listen to the many calls for restraint being made around the world, says the BBC's South East Asia correspondent, Jonathan Head.
On Wednesday, the UN Security Council held an emergency meeting in New York and called on the military junta to show restraint - a call also made by China on Thursday.
The US and the European Union wanted the council to consider imposing sanctions - but that was rejected by China as not "helpful".
Instead, Council members "expressed their concern vis-a-vis the situation, and have urged restraint, especially from the government of Myanmar", said France's UN ambassador Jean-Maurice Ripert.
They welcomed a plan to send UN special envoy Ibrahim Gambari to the region, and called on the Burmese authorities to receive him "as soon as possible".
China and Russia have argued that the situation in Burma is a purely internal matter. Both vetoed a UN resolution critical of Burma's rulers in January.
Analysts fear a repeat of the violence in 1988, when troops opened fire on unarmed protesters, killing thousands.
The protests were triggered by the government's decision to double the price of fuel last month, hitting people hard in the impoverished nation.