European governments on Tuesday rushed out travel warnings telling their nationals to take extra care and avoid crowds if they travel to riot-hit Britain. While stopping short of advising against travelling to London, or any other affected British towns, the messages were more bad publicity and potentially lost tourist revenue during the summer high season. Continental Europe's big-hitters France, Germany, Italy, Portugal and Spain all sent out travel warnings, issuing similar messages to those making business or tourism trips. "Travellers are advised to exercise special caution, to immediately pull back if confronted with any signs of disturbance, and to especially follow advice given by security forces," the German foreign ministry said in its online travel advisory. France warned the hundreds of thousands of its citizens living in Britain to be "extremely" careful when moving about London and other cities engulfed by rioting. The foreign ministry's website urged "extreme caution" if venturing out at night and said French men and women living or on holiday in Britain should at all costs avoid the "mobs" that have been forming in city centres. Dutch authorities also issued a heightened travel alert. On top of that thousands of Dutch, and English, football fans were left disappointed when a friendly fixture between the two nations scheduled for Wednesday was cancelled. "We have received clear advice that due to the sporadic and widespread nature of the unrest there are significant concerns in relation to the available emergency service resource to safely police the fixture," the Football Association said in a statement. The national tourist agency "Visit Britain" attempted to put up a brave, if not totally reassuring, face. "If you are turning on your TVs or opening your newspapers this morning and seeing scenes about 'London burning' , yes it is terrible, but rest assured, the city and this country has dealt with far worse," the tourist board said on its website. British Prime Minister David Cameron cut short his own holiday, in Italy, to return home and deal with Britain's worst rioting in decades. As the disorder claimed its first fatality, with the death of a man found shot during looting in south London, Cameron vowed to do "everything necessary to restore order to the streets" after three nights of violence. However the Portuguese government summed up many people's feelings in its own travel warning in which it said it was impossible to estimate the size of the riots. Lisbon advised its citizens "to avoid big crowds and to be very careful in the evening," when most of the trouble has flared up since the violence erupted in north London on Saturday following the fatal shooting of a police suspect. There was more to come on Tuesday night as hundreds of masked youths rampaged through the centre of Manchester, smashing windows and going on a looting spree as the worst riots for decades in Britain spread to a new city on a fourth night of unrest. There was another frenzy of violence in the industrial West Midlands. The widespread violence comes less than a year before London is due to host the 2012 Olympic Games. On Tuesday Home Secretary Theresa May vowed to review security plans for the games, amid accusations at home that the police have been unable to restore order among the rioters. May said officials would "look at what is necessary" to ensure a trouble-free Olympics, where police will be aiming to provide security for some 10,500 athletes and many more visitors.