Greenpeace activists said Monday they were blocking a train transporting nuclear waste to the French port of Cherbourg from where it was to be shipped to Russia.

Four activists who had chained themselves to the railway line near the harbour were removed early Monday morning by police but more activists were blocking the line at a different location, they said.

"We were dislodged in Cherbourg, but we are continuing our action some 20 kilometres (12 miles) from the city, where we are physically blocking the passage of the train transporting nuclear waste," Greenpeace representative Yannick Rousselet told AFP.

Two Greenpeace activists were chained to the rails just metres from the train, which had stopped, he said.

An official with French nuclear giant Areva confirmed a consignment of 650 tonnes of uranium was headed to Russia but denied that it was waste, saying it only needed enrichment.

This was rejected by Rousselet, who called for a moratorium on the export of nuclear waste.

The material is due to be loaded onto the freighter Kapitan Kuroptev to be sent to Russia.