Protesters take part in a demonstration against the military upheaval in Mandalay, Myanmar on Monday. Photo: AFP

Myanmar's military leaders came under renewed pressure at home and abroad Tuesday, with tightened sanctions from Washington and Brussels, and some of the biggest demonstrations against their rule since they seized power three weeks ago.

Authorities have gradually ratcheted up their use of force against a massive and large disobedience campaign demanding the return of ousted leader Aung San Suu Kyi. 

Three protesters have been killed in demonstrations so far, while a man patrolling his Yangon neighborhood against night arrests was also shot dead on the weekend.

Overnight the US blacklisted another two members of the authorities - air force chief Maung Maung Kyaw and fellow junta member Moe Myint Tun - after announcing targeted sanctions against other top generals earlier in February.

"We will not hesitate to take further action against those who perpetrate violence and suppress the will of the people," Secretary of State Antony Blinken said.

He called on the authorities to end attacks on protesters, journalists and activists, release prisoners detained since the upheaval, and "restore the democratically elected government."

Washington's announcement came hours after the EU approved sanctions targeting Myanmar's military and their economic interests.

"All direct financial support from our development system to the government reform programs is withheld," said Josep Borrell, the EU foreign policy chief. 

But he said the bloc would not curb trade ties for fear that it could hurt the wider population.

The Myanmar military has deployed tear gas, water cannon and rubber bullets against protesters, with isolated incidents of use of live rounds. 

They have also stepped up the presence of security forces in Yangon, Myanmar's largest city and commercial hub.

More than 680 people have been arrested since the upheaval, according to the Assistance Association for Political Prisoners monitoring group, with nearly all still behind bars. 

Overnight internet shutdowns have also become routine, fanning fears of protester arrests during the blackouts.

AFP