By Alex Kirby BBC News Online environment correspondent

UK Government documents show that waters off south-west England were used as a radioactive waste dump.

They detail the dumping of civil and military waste between 1965 and the early 1980s. In one incident, the crew of a dumping vessel were exposed to radiation.

A local politician has asked the government whether it is monitoring the waste, and whether it can retrieve it.

The documents, released by the Public Records Office, show the waste was dumped about 400 kilometres (250 miles) west of Land's End in Cornwall.

The site chosen was 2,000 metres (6,600 feet) deep, in international waters. But there is concern that some consignments may have ended up elsewhere.

All at sea

A Cornish MP, Andrew George, the Liberal Democrat member for St Ives, said some of the waste was high-level and included plutonium, which has a half-life of 24,100 years.

He said the documents also showed one trip had had problems.

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Mr George said: "The archives show that there was at least one incident, in 1969, when a full flask cracked and contaminated the MV Topaz.

"Its crew were exposed to radiation. The archives also contain reports of vessels becoming lost due to navigation problems.

"The planning was careful, but it appears that the dumping was sub-contracted to mariners with little experience in dumping such potentially dangerous substances.

"Evidence recorded by Greenpeace in the Hurd Deep showed how quickly barrels can become corroded and disintegrate.

"There is no suggestion of any present threat to marine or human life. But it is important that the government gives reassurances that no waste is unaccounted for.

"I would also welcome reassurances from it that this and other nuclear dump sites are being monitored."

The Hurd Deep lies in UK territorial waters west of the Channel Islands and close to the French coast.

Eighteen months ago Greenpeace filmed a number of corroded barrels dumped there between 1950 and 1963. A total of 28,500 barrels were disposed of in the Deep.

'Nothing new'

Mr George told BBC News Online: "In the 1970s local fishermen suspected that the dumping was happening, but so far as I know this is the first official confirmation.

"There is evidence in the documents themselves that there was difficulty in locating the actual dump site on some occasions."

A spokesman for the Department for Environment, Food and Rural Affairs (Defra) told BBC News Online: "This material has been available in all sorts of ways at least since 1984.

"The UK dumped radioactive waste at a number of north-east Atlantic sites from 1949 to 1982, when it was banned.

"The dumping was always done at depths of not less than 1,900 metres."

Different world

Another Liberal Democrat, Malcolm Bruce MP, said relying heavily on nuclear power in the future would be an unwise step for any government to take.

He said: "Since 11 September the risk of terrorist attacks on nuclear installations must be put in a different order.

"We have to recognise that we're in a new era. Perhaps you can protect a nuclear plant like Sellafield against attack, but if you're sending fuel shipments 12,000 miles (19,000 km) across the world, the risk is unacceptable."

Seabed images courtesy of Greenpeace/Newman