Witnesses said between 500 and 600 protesters, many with their faces covered, charged a fence around the Camp Garcia bombing range at Vieques to invade the land now controlled by the US Department of Interior.

The violence marred what had been expected to be a peaceful ceremony organized by Vieques people who have led an international protest campaign to force the Navy to stop using their land as a bombing range.

Campaigners said years of target practice had affected the health of the local population, including giving them one of the highest cancer rates in Puerto Rico. The US Navy has denied the allegations, saying the evidence was inconclusive.

As fireworks were set off, protesters, chanting "Vieques Yes, Navy No", burned vehicles that have been used by the Navy and destroyed several structures, police and witnesses said.

Governor Sila Maria Calderon watched from a stage set up in front of the fence's main gate where the official ceremony was to be held.

"These people who are committing these acts of violence are violating the law and the spirit of what this fight was all about," she said. Many around her booed her comments.

Police said that they could not arrest the protesters because the incidents occurred on federal property.

The former Navy property now belongs to the Department of Interior which will develop a wildlife refuge under the terms of last year's National Defense Authorization Act, which put an end to the bombing range.

The Navy, however, is responsible for cleaning up unexploded ordinance on the beaches, some which will be opened to the public.

The ceremonies, including a march through the streets of Vieques, were to continue through Thursday.

SPACE.WIRE