Frankfurt reverberates to themes from 'The Great Escape' and 'The Dambusters'

The first of what is expected to be more than 40,000 England fans began arriving in Frankfurt yesterday for their team's opening World Cup match as authorities warned them not to "cross the line" with anti-German songs.

Only 18,000 England fans have tickets through official sources for tomorrow's match and authorities believe the key to a trouble-free weekend is by accommodating ticketless fans at two giant screens in the city.

Bars in the city will be open tomorrow at 11am and temperatures are expected to climb to 28C, conditions conducive to rowdiness. The Home Office has warned England fans that they face arrest for using Nazi chants and salutes. But it remains unclear whether singing songs which recall the Second World War, as some were already doing in Frankfurt yesterday, would be cause for arrest.

Asked how his force would react to mass renditions of theme tunes from films such as The Great Escape and The Dam Busters, Frankfurt's police chief, Achim Thiel, hinted at a tolerant approach to songs that poke fun at Germans. "We have no order to police officers to interrupt this funny situation," he said.

But the Home Office minister Vernon Coaker said: "We hope that people from Britain will recognise when the fun might start to become offensive. We want people to take responsibility. Please act responsibly and think about when you cross the line between having fun and causing offence."

Police sources consider the next 24 hours to be crucial for the anti-hooligan operation; if there is trouble in Frankfurt the German police may revert to their customary hard line towards football violence. Concern centred on a group of fans singing anti-Turkish songs at an Irish bar in the city last night. Frankfurt has a Turkish population of more than 100,000, and relations between English supporters and Turks have been strained since the fatal stabbing of two Leeds fans in Istanbul in 2000.

Petra Roth, the Mayor of Frankfurt, said she was looking forward to a weekend "in the best British tradition". She said Frankfurt, Germany's fifth largest city, had a proud record of racial integration and its police were equipped to deal with its five matches, including games involving Holland and Iran - which has become the adopted team of Germany's far right. "We are ready for our British guests and we are certain we will celebrate a great and peaceful party in the best British tradition," she said.

Up to 15,000 police officers will be on duty, drawn from the surrounding state of Hessen. In an unprecedented precautionary measure, about 40 uniformed British officers will also be on the beat. Crowds will be infiltrated by plain-clothes "spotters". At least 3,500 known troublemakers have been prevented from leaving the UK, although police revealed yesterday that 180 of them, thought to still be in the UK, had not surrendered their passports. Only two banned fans have tried to enter Germany - a ticket tout with no record of violence and a hooligan turned back at the Czech border.

Uncertainty continued to surround anti-tout measures, with Mr Thiel saying that anything between "10 and 100 per cent" of fans would be checked as they entered the stadium. The organisers had planned to demand every fan shows their passport to match the ticket bearing their name, but this has raised concerns of a crush outside venues. England fans have 18,350 tickets purchased through official channels. Mr Coaker told fans not to risk buying on the black market but authorities will not know until kick-off at the 42,000-capacity stadium how effective having named tickets has been.

Three England fans, who were all from the Midlands, were arrested early yesterday minutes after they stepped off their flight from Cologne at about 1am, after they got into an argument with a taxi driver and attacked his vehicle.

The men went to court later yesterday, pleaded guilty and were fined and banned from the city.