Five days of calm ended with a volley of bottles and chairs as dozens of German hooligans clashed with police in Dortmund before their country's pivotal win over Poland. Police arrested more than 300 German and Polish hooligans over the day.

German fans were behind yesterday's worst single incident, accounting for 120 arrests. Officers, seeking to apprehend a group of known German hooligans, came up against men throwing bottles and chairs and shooting fireworks, said Dortmund police chief Hans Schulz. Several people were injured before the situation was brought under control. Schulz said 100 hooligans managed to flee. "It was not a good atmosphere in Dortmund," Mr Schulz said.

In Nuremberg, where an estimated 50,000 England fans are congregating for their team's second match, police said they were ready should any more disturbances arise.

"It's possible we will face the same thing," policeman Joachim Hagen said. "We have a strong force and we will keep a close watch."

Overnight, two England fans were arrested for assault and another three people were detained for throwing plastic bottles, but later released, British police said.

Assistant Chief Constable Stephen Thomas, of the Greater Manchester Police, who is helping British police work with their German counterparts, said that overnight the city was calm as Germans celebrated their win by taking to the streets, cheering and drinking. "I hope our players' rooms were soundproofed," he said, referring to the raucous cheering by German fans outside of the Grand Hotel where England players stayed the night. The hotel is also near an Irish bar where England fans have been congregating and German police moved to prevent the two groups from coming into contact with each other. "German fans are like England fans. They drink a lot, make a lot of noise and have their own party," Thomas said.

Since the tournament's June 9 start, Thomas said 46 British nationals have been arrested, part of the more than 1,500 people arrested across the country.

The threat of fan violence had been a major theme ahead of the month-long football tournament — and England's supporters were often cited as one potential danger. At the 2000 European Championship, co-hosted by Belgium and the Netherlands, 945 Britons were arrested for soccer violence. The most severe rioting was in Charleroi and Brussels and led to European soccer administrators threatening England with expulsion from the tournament.

At the 1998 World Cup in France, German hooligans beat a French policeman nearly to death and England fans rioted in Marseille. To head off trouble, authorities across Europe confiscated the passports of known troublemakers, increased border patrols and drew up extensive policing plans for the dozen game cities.

But, before yesterday, tranquility in World Cup-hosting cities had allayed much of the fear over widespread hooliganism at football's biggest event and even surprised police who had braced for the worst. "On a normal Sunday there might have been more for the police to do," said Nuremberg police spokesman Michael Gaengler after his city's first match, between Mexico and Iran.