STRASBOURG, France - Anti-NATO protesters torched buildings, ransacked shops and hurled petrol bombs at police on Saturday in a violent rampage on the fringes of a summit of the military alliance's leaders.

A seven-storey hotel and numerous stores were gutted during the rioting, the ferocity of which seemed to take security forces by surprise in the French city of Strasbourg.

Police withdrew from an area close to the Rhine river at the height of the violence, failing to intervene as hundreds of masked youths tore into the working class district.

It is disgusting. There wasn't a single policeman protecting this neighborhood. They would have never done this in a beautiful neighborhood, complained local resident, Christine Kiefer, surveying the destruction.

Riot police eventually fought back, firing hundreds of rounds of teargas and stun grenades to try to regain control. Protesters dragged a rail carriage on to the road and shot fireworks into police ranks and into nearby houses.

Guests were evacuated from the IBIS hotel as the flames took control and locals said it took too long for the emergency services to come to their rescue.

German water cannon, held on the other side of the Rhine in case of crowd problems there, were called over to help tackle the blazes that cast a pall of thick black smoke into the sky.

Police said they made several arrests, but gave no further details, and health authorities reported no serious injuries.

The worst of the violence was centered close to the French side of the Bridge of Europe -- a road link over the river Rhine which connects France with Germany.

The bridge is 5 km (3 miles) from the center hosting the NATO summit, and close to a footbridge which the 28 leaders, including U.S. President Barack Obama, had crossed earlier in the day in a ceremony symbolizing the unity of the alliance.

Rioting broke out later and never threatened the summit venue.

PROTEST ORGANISERS SHOCKED

The demonstrators campaigning to have NATO disbanded following the end of the Cold War had vowed to disrupt Saturday's meeting after two days of skirmishes with police.

However, activists said they had wanted to use peaceful methods and expressed shock at the violence.

I have been on countless peace marches for four decades, but I have never seen anything like this. There were no police around when they started to burn things, said Hartmut Brewes, 70, a retired pastor from Bremen in north Germany.

Between 10,000 and 30,000 people took to the streets of Strasbourg and around 7,000 joined an anti-NATO rally in nearby Baden-Baden, just across the German border.

Protest organizers said the vast majority of them took no part in the violence and blamed tensions on security forces.

Police said some of the protesters who left a designated demonstrators' campsite near Strasbourg early on Saturday were armed with sticks, barbed wire and stones hidden in sacks.

Marie-George Buffet, a veteran leader of the French Communist party, said the violence had nothing to do with the peace movement.

I am very angry. This was meant to be a peaceful demonstration ... and tonight, instead of images of peace we will see images of war, she said.

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