Violence has broken out in Berlin for the second night running as Germany celebrates the annual May 1 holiday. The anarchist riots seen in Berlin and Hamburg Tuesday night did seem to have been kept in check during the daylight hours Wednesday.

It has become a tradition in Germany, and especially in the capital city Berlin: anarchist groups flood into the big cities to indulge in street violence during the May Day holiday.

They unleashed their aggression early this year, rampaging through the streets of Hamburg and Berlin Tuesday night, throwing stones, looting shops and attacking police.

One 18-year-old woman was taken to the hospital Wednesday, in critical condition after being hit over the head with a bottle. She was reportedly just a pedestrian who got caught up in the attack on the fringes of a huge party in the center of Berlin. Scores were arrested overnight.

During the daylight hours of Wednesday, however, things started out quieter.

Hundreds of thousands gathered for peaceful May Day demonstrations in cities all over Germany in support of trade union demands for a 6.5 percent pay raise and threats of strike action.

But elsewhere, neo-Nazi groups marched through a number of cities. They found their passage blocked by police or by jeering counter-demonstrators, opposed to the racist, anti-Jewish and anti-American message of the far right. And in some places, there were violent clashes between the opposing factions.

The anarchist violence seemed to have died down during the day. But the tension mounted as the afternoon drew to a close. In Berlin, demonstrators waved pictures of the late Chinese Communist leader Mao Zedong and chanted revolutionary slogans, while others have been marching to protest Germany's military backing of America in the war against terrorism. Others were seen waving Palestinian flags.

And shortly after 7 p.m., Berlin's Kreuzberg district erupted in violence again. Youths threw stones and looted a supermarket before the police moved in to break up the riot.

The police were widely criticized last year for heavy-handed intervention, which was said to have provoked the crowd to violence. So this year they have deliberately held back, patrolling in ordinary uniforms and remaining only lightly armed.

But police spokesmen say they are ready to respond quickly and in full riot gear at the first hint of violence. The signs are they will have to make good on that promise several times before the night is out.