Tens of thousands of people rallied over the weekend and the movement built on Monday with more protests and the start of a general strike.

The junta, which ousted civilian leader Aung San Suu Kyi in a lightning coup a week ago, has so far refrained from using deadly force to quell demonstrations, but with pressure growing police fired water cannon to disperse protesters in Naypyidaw.

A statement read by an announcer on state-run MRTV said there had been violations of the law and threats of force by groups "using the excuse of democracy and human rights".

"Action must be taken according to the law with effective steps against offences which disturb, prevent and destroy the state's stability, public safety and the rule of law," the statement said.

The military -- which ruled Myanmar for nearly half a century -- seized power after complaining its allegations of fraud in November's general election were not being investigated properly.

During junta rule dissent was vigorously quashed and the military frequently used lethal force, notably against huge protests in 1988 and 2007.