The first of the protesters arrived more than a year ago

On arrival, hundreds of US marshals and FBI agents, wearing helmets and bullet-proof vests, gave the protesters a choice of abandoning the base voluntarily or being placed under arrest.

When no-one moved, the agents began handcuffing them, to end the year-long sit-in.

Those arrested included two Democratic Congressmen, who had joined the protest earlier in the week, as well as local politicians, priests, actors and singers.

Ms Reno expressed satisfaction at what she called the smooth operation, noting that the protesters had conducted themselves in a "peaceful and dignified manner".

She said the law had been enforced in a fair and measured way.

Ms Reno added that the US Coast Guard had established a security zone in the waters around the base to prevent further protesters arriving by boat.

The protesters have vowed to do what they can to block future military operations there.

Live bombs

They have already forced the US Government to agree to stop using live bombs in its training, and to contemplate ending the exercises altogether.

The first of the demonstrators arrived at the base more than a year ago, shortly after a navy pilot accidentally killed a civilian guard in a bombing exercise.

Navy ordnance lies scattered around the island

Local people say the military has damaged the Vieques environment, ruined its economy and caused an unusually high cancer rate on the island.

The navy, for its part, insists the base is vital to national security as it is the only place it can run simultaneous air, sea and land exercises using live ammunition.

A raid to clear the base had been expected since 1 May, when three US warships, reportedly carrying 1,000 Marines, arrived in the Vieques area.

The BBC's Stephen Sackur in Washington says arguments over the base are likely to intensify even as the protest camps are dismantled.