Gorleben, Germany - Fierce protests accompanied the arrival of a shipment of radioactive waste at a northern German warehouse early Tuesday, one day behind schedule, after thousands of anti-nuclear activists tried to hold up the convoy.

After more than 80 hours stopping and starting by train and truck, 11 containers with spent nuclear fuel from German nuclear power plants arrived at Gorleben in Lower Saxony state just after midnight.

Twice, protesters chained themselves to ingeniously designed concrete weights which had to be cut up, piece by piece, to release cuffs around the protesters' wrists without injuring them.

Each time the convoy had to wait about 12 hours. One of the weights, near the French border, could not be moved because it was under the rail bed. On a road near Gorleben, interlocking weights one metre tall could not be lifted for fear of causing cuts.

Police said the protests, which had accompanied each of the 10 previous transport operations down the years, were on a larger scale, with 15,000 demonstrators near Gorleben, and also more violent than usual.

Protesters had tried to undermine a railway, thrown fireworks and shot signalling flares at a police helicopter.

About 1,000 protesters who blocked the entrance to the warehouse had to be carried away Monday, one by one, by riot police.

On Tuesday, the demonstrators had vanished and only the debris, including burned barricades and food scraps, was left.

"It's always like that after these demonstrations," said Peter Hoppe, police spokesman. "From one moment to the next, it's all over."

Environment Minister Sigmar Gabriel criticized the protests, saying blocking the railway was "not acceptable."

Rainer Wendt, chairman of a police union, slammed the non-confrontational tactics employed by police commanders.

Protest leaders and police chiefs held regular consultations throughout the conflict.

"The state was made to look foolish by the anti-nuclear activists," he said. At one point, three protesters managed to clamber on a railway truck carrying the highly radioactive waste.

The activists urged the government to quit nuclear energy and announced further protests against a plans to move all the waste accumulated at Gorleben from the warehouse to an underground salt-mine.

Although Germany is legally obliged by 2030 to set up a storage site where the waste can be safely kept for centuries, Berlin has held off designating Gorleben as that site and hinted it might consider other locations. The issue remains frozen.

The protesters, who reject nuclear power as unsafe, aim to draw attention to the issue by disrupting the convoys. Under legislation, Germany is to close all its nuclear power plants within the next 15 years.

The trip began at a reprocessing plant in La Hague, France which encased the hot waste in glass to keep it inert for centuries.

The next convoy is not expected at the storage warehouse till 2010. (dpa)