German police battled thousands of anti-nuclear protestors Sunday, many chained to railroad tracks, who have caused delays as they try to block a train carrying radioactive waste.

The convoy taking the German waste on a 1,200-kilometre (750-mile) journey from a reprocessing centre in northwestern France to a storage facility in northern Germany was at Lemgrabe, about 30 kilometres (19 miles) away from its final destination of Dannenberg, at 1800 GMT.

After already stopping for 18 hours, including overnight, amid mass demonstrations, the train had only covered around 30 kilometres in four hours.

Thousands of activists swarmed the tracks along the route near the train's final destination in Dannenberg and boasted that the odyssey's duration had now topped the 92-hour record set during a shipment one year ago.

Police said they detained about 1,300 people, including some who had chained themselves to the railway, requiring tricky and time-consuming operations to free them before the train could slowly rumble on.

Some 150 people were injured in clashes, most of them demonstrators, according to security forces quoted by German news agency DPA.

The waste, produced in German reactors several years ago and then sent to France for reprocessing, began its journey in a yard operated by French nuclear company Areva in Valognes, Normandy Wednesday.

The protestors argue that the shipment by train of spent fuel rods is hazardous and note that Germany, like the rest of Europe, has no permanent storage site for the waste, which will remain dangerous for thousands of years.

They are also angry that a pledged German phase-out of nuclear power, hastily agreed this year in the wake of the Fukushima disaster in Japan, will take another decade to implement.

"It's like a friend telling you that he will stop smoking in 10 years," said Jochen Stay, spokesman for the anti-nuclear body Ausgestrahlt (Radiated), which has mobilised protesters against the shipment.

"You are not going to congratulate them just yet."

At the train's final destination of Dannenberg, the 11 containers of waste are due to be unloaded onto trucks for the final 20-kilometre leg of the journey by road to the Gorleben storage facility on the River Elbe.

Organisers said about 23,000 protestors had gathered in Dannenberg, while police put the number at 8,000. About 20,000 police have been deployed along the train's German route.

The demonstrators had travelled from across Germany as well as from Belgium, the Netherlands, France and Italy, organisers said.

The train's disputed load represents "44 times Fukushima", according to ecology group Greenpeace, which said a single container could unleash "four times the radioactivity released" by the stricken Japanese nuclear reactor.

The bulk of the protests have been peaceful.

"We've had campfires, music, and brought in food" for the activists in chilly temperatures, an organiser, Mechthild Magerl, told AFP.

But there were isolated outbreaks of violence Thursday and Friday near Gorleben where 10 masked rioters attacked police with bricks and smoke bombs before managing to escape.

Police said unidentified assailants hurling Molotov cocktails Friday damaged two patrol cars.

In November 2010, about 50,000 protesters delayed a similar shipment by a day. Since then, Berlin has agreed to shut down all 17 of the country's reactors by the end of 2022.

Germany had already decided in 2005 to stop shipping radioactive waste overland for reprocessing in favour of permanent storage.

However it is contractually obliged to repatriate waste sent abroad before that date and has yet to designate a final storage site.

Environmentalists say that nuclear radiation in the Gorleben zone exceeds the authorised levels.

This is expected to be the last such shipment from France. But from 2014, nuclear waste will be transported to Germany for storage from a British processing plant at Sellafield.