At least 20 German policemen have been injured during clashes with protesters ahead of the arrival of a shipment of nuclear waste in northern Germany, police sources say.

Police said some 300 protesters threw stones and fireworks at security officers near the town of Dannenberg on Saturday.

The attack followed a clash on Friday night when police used water cannons and batons to keep some 200 protesters in check. The officers were injured during the clash.

The protests occurred near the railway tracks used by a train this weekend to transport the nuclear waste shipment reprocessed in France to a storage site near the town of Gorleben.

'Zero chance'

Some 20,000 officers are on hand in the region to secure the shipment.

Officials have yet to resolve where such waste should be stored permanently. Activists say Gorleben is unsafe.

Al Jazeera's Nick Spicer, reporting from Dannenberg, said the protesters had "zero chance" of blocking the train.

"There's no chance the train will be stopped. That's how it has happened in the past," he said. "The people are saying they don't want nuclear waste to be stored in Germany any more."

Germany is phasing out its nuclear facilities following the disaster triggered in March by an earthquake and tsunami at Japan's Fukushima nuclear plant.

Angela Merkel, the German chancellor, has said all the country's remaining nuclear capacity would be taken off the grid by 2022.

Source: Al Jazeera and agencies