Radiation from the plant was found in food

Environment minister Elliot Morley said the nine-month moratorium would affect low level emissions.

The call comes amid reports that traces of radioactive waste from the reprocessing plant have been found in salmon on sale in major supermarkets.

The Greenpeace-commissioned study, by Southampton University's oceanography department, found the fish contained traces of Technetium-99 and emitted very low levels of radioactivity.

Demands for action are expected later this week at the Convention for the Protection of the Marine Environment of the North East Atlantic (OSPAR) Convention, which began in Bremen, Germany on Monday.

The Irish government has put constant pressure on Britain to close Sellafield because of fears over the risk of radioactive pollution spreading across the Irish sea.

Norway has also voiced concern because it has one of the world's largest salmon farming industries.

Technetium-99 has already been found in seaweed and shellfish off the Norwegian coast.

Elliot Morley: Foreign governments have welcomed ban

Mr Morley said Environment Secretary Margaret Beckett had asked Sellafield operator British Nuclear Fuels Limited (BNFL) to act and the UK government believed a nine month ban was not an "unreasonable" length of time.

He said Nirex, the agency responsible for the disposal of nuclear waste, believed that it would now be feasible to introduce a new storage process for waste.

Mr Morley said: "We have written to BNFL to ask them if they will put a moratorium on Technetium-99 emissions, pending this new research and putting the new procedures in place.

"That has been welcomed by the Norwegians although we have not yet had a reaction from the Irish.

"But Norway and Ireland have long expressed concerns about traces of Technetium-99 being found in shellfish in particular.

"You can find it in fish as well although these trace levels are not considered a risk to human health.

"If you can detect it in some fish species then perhaps it is no surprise that it is detectable in farmed salmon.

"All the advice from the Environment Agency and Nirex is that these are very low levels and no risk to human health.

"But nevertheless I think it is desirable that we take every step to make sure we don't get these trace elements in fish and shellfish."