Tens of thousands of protesters were on the streets of Yangon yesterday in the biggest rally yet against the Myanmar coup as an internet blackout failed to stifle outrage at the military's ouster of elected leader Aung San Suu Kyi.

Some estimates put the number of protesters in Yangon at 100,000, and there were reports of big demonstrations in other cities against the coup that halted Myanmar's 10-year experiment with democracy.

Chanting protesters in Yangon carried banners reading "Justice for Myanmar" while others waved the red flags of the National League for Democracy party as they marched to City Hall.

"I completely despise the military coup and I'm not afraid of a crackdown," said university student Kyi Phyu Kyaw, 20.

Police blocked protesters at several points, but a huge crowd was able to gather near Yangon City Hall without any clashes. Some protesters handed out roses to policemen.

"We'll fight to the end," said economics student Ye Kyaw, 18. "The next generation can have democracy if we end this military dictatorship."

The surge in dissent overcame a nationwide internet blockade, similar in magnitude to an earlier shutdown that coincided with the arrest of Suu Kyi and other senior leaders last Monday.

There were also protests in Mandalay, Myanmar's second-largest city, and Mawlamyine.

As protests gathered steam, the junta ordered telecom networks to freeze access to Facebook. The platform had hosted the a disobedience movement that has inspired civil servants, health care professionals and teachers to boycott their jobs.

Besides Suu Kyi and top aides, about 150 people have been detained.

The junta has insisted the NLD's landslide victory in the November elections was the result of widespread voter fraud and proclaimed a yearlong state of emergency.

As protesters march in Yangon demanding the release of Aung San Suu Kyi, police set up road blocks. REUTERS, AP

Protest marches defy Myanmar junta clamps