STRASBOURG (AFP) - Protesters clashed with riot police and set property ablaze in Strasbourg during Saturdays 60th anniversary NATO summit, leaving at least 10 people injured, the French government said. Despite a 10,000-strong deployment of security forces, militants managed to set fire to a hotel near the Rhine bridge where US and French presidents Barack Obama and Nicolas Sarkozy had assembled earlier for a photocall. Hardcore anarchist groups, calling themselves Black Blocks, splintered off from the main body of protestors, which numbered 30,000 according to organisers and 10,000 according to police. Firefighters intervened to put out flames at the Ibis hotel, one in an international chain of French economy-priced hotels. Six demonstrators and four police officers suffered injuries, Interior Minister Michele Alliot-Marie told France 3 television, adding that a certain number of the protesters had been overcome by teargas. Some 100 masked demonstrators armed with metal bars also wrecked a chapel and other buildings at the French end of the Europe bridge connecting Strasbourg with Germany. On the roof of the chapel they wrote a quotation from 19th century French writer Victor Hugo: Religion is nothing but the shadow cast by the universe upon human intelligence. A service station was also looted and volunteer medical teams attached to the march claimed that protesters had been injured by rubber bullets. The tension saw a planned visit to a cancer research centre for spouses including Michelle Obama and Carla Bruni-Sarkozy scrapped and replaced by a museum and cathedral tour. The militants were in the vanguard of clashes with French riot police using water cannon and tear gas ahead of the 3:00 pm (1300 GMT) starters gun for what organisers had promised would be a monster rally. Police were equipped with batons, helmets and body armour backed up by helicopters buzzing overhead. Many demonstrators were masked and wore black, brandishing red and black flags, peace banners, beating drums and carrying pictures of Latin American revolutionary icon Che Guevara. Some came prepared with their own gas masks. The road was littered with signs of previous clashes: a smouldering barricade, broken glass and spent tear-gas grenades giving off an acrid smell. Several protesters chanted NATO means war 60 years is enough They also waved banners reading Make NATO History, and, in a swipe at Obamas presidential campaign slogan, Quit Iraq and Afghanistan. Yes We Can. On the German side of the Rhine, a comparatively peaceful group of 5,000 to 6,000 protesters, according to a police tally, were prevented from crossing into France. We are disappointed, of course, said their spokesman Dieter Lachenmayer. We wanted to join our French friends so that the demonstration could be international. A Franco-German river patrol arrested around a dozen divers from environmental group Greenpeace who attempted to enter the Rhine in wetsuits ahead of the Obama-Sarkozy photocall. And as the 28 NATO leaders held talks, up to 200 demonstrators penetrated the outer security cordon and blocked traffic. We are near the congress centre.... It is a first victory for us because President Sarkozy said that he didnt want to see demonstrators on the street, a 45-year-old German protester told AFP. Around 100 riot police lined out across the flashpoint bridge the focus of cat-and-mouse antics since Thursday waving marchers through a small gap around a dozen at a time. Elsewhere Saturday, more than 1,000 people demonstrated in Istanbul against Obamas visit to Turkey from Sunday night through Tuesday. There was also protest by about 300 people in Prague, where the president arrived late Saturday.