About 5,000 Burmese monks have been joined by nuns for the first time on the seventh day of protests calling for an end to the military government.
The protest is gaining strength, observers say
Cheered on by 10,000 onlookers, up to 150 nuns joined the march through the heart of Rangoon.
But unlike a day earlier, police barred a group of monks from entering the road that leads to the home of detained opposition leader Aung San Suu Kyi.
The protest is the biggest public show of opposition since the 1988 uprising.
BBC South Asia correspondent Jonathan Head says the demonstrations are escalating because the monks are now urging civilians to join in, after advising them last week not to get involved.
The head of regional grouping Asean, Ong Keng Yong, told the Associated Press news agency he hoped the Burmese authorities would not take any strong action "and turn the protests into a big confrontation".
Apparently unsure what to do, the security forces appear to be standing back for the moment and the next act in the drama is impossible to predict, says our correspondent.
Ms Suu Kyi emerged tearfully on Saturday from the home where she has been under house arrest since 2003 to pray with the monks, after they were allowed through a roadblock.
But on Sunday the barricades were firmly back in place and there was a heavy security presence near the democracy icon's home to prevent a repeat protest march past.
Witnesses said the crowds formed a protective human chain, as the monks and nuns set off from Burma's most famous landmark, the revered Shwedagon Pagoda.
Some demonstrators chanted "Release Suu Kyi" as they continued to the nearby Sule Pagoda, before passing the US Embassy.
Nobel Peace Prize Laureate Ms Suu Kyi has spent 11 of the last 18 years in detention.
In 1990 her party won national elections, but these were annulled by the army and she was never allowed to take office.
On Friday, the Alliance of All Burmese Buddhist Monks, which is leading the demonstrations, vowed to continue until they had "wiped the military dictatorship from the land".
The monks have urged the Burmese people to hold prayer vigils in their doorways for 15 minutes at 2000 (1330 GMT) on Sunday, Monday and Tuesday.
The rallies began last month when the government doubled fuel prices.
But they have taken on new momentum in the past week since the religious order became more widely involved.
On Saturday, at least 2,000 monks took to the streets in Rangoon, 10,000 monks went on the march in Mandalay and there were protests in five townships across Burma.