Editor's Note: Why would U.S. Security Forces try to get C4 past German security? This could have very well been an attempt to blow something up and blame it on the protesters so security could violently crack down on them.

Heiligendamm, Germany (dpa) - Greenpeace protesters in several inflatable boats forced their way into a marine exclusion zone near the G8 summit at Heiligendamm in Germany on Thursday.

High-speed police patrol boats and inflatables gave chase for 10 minutes in a spectacular display of dodging on the Baltic before the protesters were caught. One of the protest boats capsized.

A Greenpeace spokesman said the group had intended to land on the beach outside the luxury summit hotel and hand a petition to Western leaders demanding action on climate change.

The previous day, police had confiscated motor parts for the inflatables on the Greenpeace mother ship Arctic Sunrise in a vain effort to nip the protest in the bud.

On land, police allowed protesters to assemble peacefully for a second day at a fence two kilometres from the G8 summit venue.

German authorities have legally prohibited protests in the area, but police have been pragmatic, insisting only that protesters do not touch the fence. Riot police have manhandled protesters away from essential roads only.

"We're only clearing roads if they are needed by us, other transport operations or emergency services," said a police spokesman.

On Wednesday, 9,000 protesters objecting to the three-day meeting of Western leaders had swarmed through fields to the fence.

At one gate to the summit compound, about 1,000 protesters spent the night in sleeping bags. At another access way to the east, 500 slept on the ground. Protest helpers hauled in food and portable toilets for them.

German police, who have 16,000 personnel at the summit, have called up reinforcements. Police unions said 200 riot police from Hamburg and 230 from Saxony-Anhalt state had been drafted to Heiligendamm to help with crowd control.

Police said they were concerned about violence, because protesters had been seen making petrol bombs or inserting nails in potatoes to use as missiles. Protesters had also planned to tie down riot police with diversions.

German police are under legal restrictions, and cannot use firearms against protesters on land or at sea.

On land they have have manhandled sitting protesters or hosed down larger groups with cold water from police trucks. Lines of riot police have used plastic clubs and shields to drive back the protesters.

Sources told Deutsche Presse-Agentur dpa that US security men tested German security by trying to smuggle C4 plastic explosive past a checkpoint at Heiligendamm.

German surveillance machinery detected the tiny stash in a suitcase in a car and the Americans in plainclothes then identified themselves. German police declined comment.