METZINGEN, Germany - Police clashed Sunday with activists trying to halt a train carrying nuclear waste from France to Germany as protests against the shipment turned increasingly violent.

Police used batons and pepper spray to disperse around 250 anti-nuclear activists who were trying to sabotage the railway tracks, and the activists hurled firecrackers back, police spokesman Markus Scharf told AFP.

A spokesman for activist group "Aktion Castor" said the police had responded with tear gas and water cannon. The woods around the train tracks are "completely clouded with tear gas," said Christoph Kleine.

Earlier Sunday, a pair of activists, backed by around 50 others, managed to hold up the train for around two-and-a-half hours by abseiling from a bridge, police spokeswoman Cora Thiele said.

Meanwhile, police carrying out checks on three vehicles discovered equipment designed to allow people to chain themselves to the track, authorities in Dannenberg said. Sixteen people were taken into custody.

Despite the delays, police said the train was continuing on its journey towards its final destination, the storage facility of Gorleben, in central Germany.

"The train is running normally," a police spokesman told AFP early Sunday.

Environmental pressure group Greenpeace said the train was near Lehrte, around 150 kilometres (93 miles) southwest of Gorleben.

"We're expecting the train some time today, but the closer it gets to Dannenberg, the more actions there will be to stop it and the slower it will travel," a Greenpeace spokesman told AFP.

When the 14-carriage train, dubbed by activists "the most radioactive ever", arrives in Dannenberg, its cargo will be transferred onto lorries for the final 20-kilometre stretch to Gorleben.

Hauke Nissen from the group "WiderSetzen" (Resist) said activists were running drills to practice sit-down protests to block the tracks.

Greenpeace has called for the train, carrying 123 tonnes of radioactive waste sent back from France after retreatment, to be stopped immediately "in the interests of public safety."

On Saturday, tens of thousands of protesters gathered in Dannenberg to signal their opposition to the cargo. Organisers said 50,000 people had turned out but police said the figure was closer to 20,000.

German Chancellor Angela Merkel denounced an attempt on Saturday to damage the tracks near Dannenberg.

Around 16,000 police have been mobilised to deal with the protests in Germany.

Germany's anti-nuclear campaigners have been outraged by a vote in parliament to extend the life of the country's 17 nuclear reactors which previously were meant to come offline in 2020.

Opinion polls show that most Germans oppose parliament's decision. Earlier Saturday, the train ran the gauntlet of hundreds of French protesters.

The train is returning German nuclear waste for storage after it was treated in France by the Areva group but activists say the facility at Gorleben is not fit for the task.

This convoy is the 11th of its kind. A previous nuclear waste shipment sent over in 2008 was blocked for 14 hours by protesters, amid a violent stand-off.