A ship carrying 650 tons of uranium waste arrived in Russia's second largest city, St. Petersburg, Greenpeace said on Monday.

The dangerous cargo of uranium hexafluoride (UF6), which belongs to the French nuclear energy group Areva, was then loaded onto railway cars to be transported to the Siberian Chemical Combine in the Tomsk region, the statement added.

The Russian vessel, the Kapitan Kuroptev arrived in St. Petersburg in the early hours of Monday. The ship had already been a source of controversy after a group of nature activists tried to stop it from entering the port in 2005 when it was carrying a similar cargo of spent nuclear fuel.

According to international standards, however, uranium hexafluoride is not considered nuclear waste, and can be transformed into fuel to release energy for nuclear power stations.

France's Areva and Britain's Urenco, a European consortium which supplies equipment to enrich uranium for the nuclear industry, has shipped some 140,000 tons of nuclear waste over the last 15 years to Russia.

While Russia's state-controlled civilian nuclear energy corporation Rosatom maintains that shipments of uranium hexafluoride will be halted by the end of 2010, Areva is determined to hold to contract conditions which it says expire in 2014, Greenpeace said on its Russian website.

"[Head of Rosastom] Sergei Kiriyenko said back in 2006 that [Russia's nuclear waste treatment] contracts would not be extended. Armed with this knowledge, radical environmental groups are deliberately straining the tension, so that they can later brag: 'See, we protested and the government gave in!' This is the goal of their campaign, it will justify their protests in mass media," a Rosatom source told RIA Novosti.

The French government set up a special ministerial commission after a documentary on nuclear waste shipments to Russia was showcased in France in October 2009. The commission's report highlighting the legitimacy of the contracts is due to be completed by the end of February.

"That's exactly why the French nuclear energy groups, including Areva, are speeding up shipments of nuclear waste to Russia," Vladimir Chuprov, the energy program director of Greenpeace Russia, said on Monday.

By 2013, Rosatom plans to complete construction of a storage facility for exported nuclear waste at Ust-Luga on the shores of the Baltic Sea. It will start operations later this year to store cargoes of uranium hexafluoride shipped in from Europe.