In a parliamentary answer to Dr David Clark, Labour's defence spokesman, it was disclosed that up to 145,000 tons of chemical weapons, including mustard and phosgene gas and the nerve agent Tabun, had been dumped around the British coast between 1945 and1957.
The sites are between 50 and 100 miles west of the Hebrides, 80 miles north-west of Northern Ireland, 250 miles south-west of Land's End and in Beaufort's Dyke in the North Channel, north of Scotland.
Nicholas Soames, the armed forces minister, said the sites had not been monitored because the water is too deep.
"Current scientific evidence indicates that such CW [chemical weapon] dump sites present no significant risk to human health or to the marine environment," Mr Soames said.
But Dr Clark, MP for South Shields, last night criticised the lack of supervision and demanded immediate scientific tests at sea sites around Britain.
"Clearly we now have the scientific knowledge to know better than to have disposed of these chemical weapons at sea. They are the real `nasties' of chemicals and it is imperative that we monitor any after-effects," he said. "After this period of time, the chemicals may be escaping from their containers and we need to know."
John Sprange, disarmament campaigner for Greenpeace, called for such sites to be mapped so that they could be avoided by commercial fishing vessels. "We need to carry out remedial work. We need to know the state of the canisters and whether the stuff is leaking," he said. Most of the weapons were dumped by loading them on to vessels which were sunk. It was reasonable to expect that the canisters would deteriorate at a similar rate, leaving the possibility of a sudden widespread release of chemicals intothe sea.
"Very little work has been done on how these chemicals disperse. There is also the danger that fish tend to congregate around wrecks," he said.
Chemical weapons tended to emerge into the sea in jelly form. Plankton could ingest the chemicals, polluting the food chain from the bottom up and little research has been done on the effects of such releases on the food chain.
Mr Sprange urged immediate checks on the state of the canisters, to see whether moving them would be possible. But even disposing of the weapons on land was a long and expensive process.Reuse content