Britain keeps lid on Baltic dump site of Nazis' deadly weapons

Thousands of tons of chemical weapons dating back to the Second World War have been rusting away at the bottom of the Baltic Sea and are beginning to leak, scientists and environmentalists have warned.

Thousands of tons of chemical weapons dating back to the Second World War have been rusting away at the bottom of the Baltic Sea and are beginning to leak, scientists and environmentalists have warned.

A poisonous legacy of Nazi Germany, more than 300,000 tons of weapons confiscated by the Allies were dumped between 1945 and 1947. The toxic stockpile includes nearly 65,000 tons of mustard gas, nerve agent sarin and the notorious death camp gas, Zyklon B.

Under the terms of a pact drawn up in 1945 between Britain, America, France and Russia, the allies agreed that the weapons would be disposed of at sea. According to Russian officials, Britain and the US had planned to offload their lethal cargo 4,000m down in the depths of the North Atlantic but were forced to scuttle their flotilla in the shallower Baltic after hitting bad weather. The Russians dumped their share of the German weapons even closer to coastal waters at a depth of only 130m in some instances.

More recent research has revealed four known dump sites: Gotland Deep, near Latvia and Lithuania; Bornholm Deep near Denmark, Skaggerak near Sweden and Norway; and Little Belt close to Denmark and Germany. Russia is the only Baltic country relatively distant from those ecological hotspots but it has led efforts to raise awareness of the problem.

Regional governments have downplayed risks but a scientific mission based in the Russian enclave of Kaliningrad has joined Green groups in warning that the impact of a simultaneous release into the ecosystem could be devastating.

Professor Vadim Paka of the Shirshov Institute of Oceanology - which earned worldwide renown working on the deep water filming in James Cameron's blockbuster Titanic - has been monitoring suspected dump sites since 1997.

His research team has taken samples from a number of sites and was alarmed to find increasing instances of mustard gas in the Baltic Sea.

"Some shells will take 50 years, some 100 years but large numbers of these weapons could corrode at the same time," the professor warned.

Environmentalists agree and warn that a widespread leakage could spell the end of the region's fisheries and tourism sector. "It would unquestionably be a catastrophe with very, very strong effect on the whole ecosystem," Dimitri Litvinov, spokesperson for Greenpeace Sweden said.

Greenpeace have been assessing the results of an independent study and are concerned the extent of any environmental damage would be exacerbated by the geography of the Baltic Sea, a body of water almost entirely enclosed by land.

It could be Britain, which preferred to scuttle entire ships rather than the Russia's approach of tossing shells overboard that has left the deadlier problem. Although their ships were sunk with the intention of sealing off the cargo at the deeper dump of Skaggerak, the rusting containers are more likely to burst simultaneously in the kind of leak Mr Litvinov is warning of. Scientists have accused Britain of failing to cooperate by classifying vital documents on dump site locations. Neither the Foreign Office or the Ministry of Defence could confirm or deny these allegations when contacted.

A 1996 study commissioned by the Finnish-based Helsinki Commission (Helcom) concluded there was no immediate cause for concern and any attempts to salvage the materiel would be more dangerous than leaving it on the seabed.

Their scientists argued chemical agents would dissolve harmlessly upon contact with water. But Professor Paka believes their studies have ignored one chillingly unique feature of the sunken arsenal. Nazi scientists commissioned a special new formula of mustard gas for the first winter of their troubled Russian campaign amid concerns it would not withstand the freezing temperature. The "winter mustard" they delivered contained 37 per cent arsenic, creating a viscous substance that Professor Paka maintains is insoluble. Officials estimate 20 per cent of Germany's entire poisonous gas production is down there, including almost all the winter gas.

Russian scientists have voiced concerns that Helcom's conclusions are now out of date and governments are afraid to act for fear of sparking a public panic and a long-term recession for fisheries and tourism. A large number of accidents involving fisherman trawling vintage shells off the seabed led Helcom to release detailed guidelines on treating victims of exposure to chemical weapons. Officials reported 36 instances of munitions being dredged up by nets. Even the slightest contact with mustard gas can lead to burns and permanent blindness, the guidelines warn, and heavy waterproofs provide no protection against these antique killers.

A consensus is emerging on a solution that would involve coating the munitions in a special concrete but the cost could be as high as $3bn (£1.8bn).