Germany on Monday lashed out against a deadly crackdown on protesters in Myanmar, summoning the Southeast Asian nation's ambassador to express its condemnation.

"Such deadly violence against peaceful demonstrators can not be justified," said Chancellor Angela Merkel's spokesman Steffen Seibert, voicing "consternation" over the crackdown.

The junta is battling to contain a massive street movement demanding it yield power and release ousted civilian leader Aung San Suu Kyi, who was detained along with top political allies at the start of the month.

Sunday brought a significant escalation in force, with fatal shootings of protesters in at least four cities around the country, as police and soldiers attempted to bring the civil disobedience campaign to heel.

Condemning the violence, Seibert said the German government urged the military junta to end its crackdown and to "exercise utmost restraint".

Berlin also called on the regime to return to a democratic process through dialogue and to release Suu Kyi. 

"We summoned Myanmar's ambassador today to make this position clear," said a spokesman for the foreign ministry.