Martin Meehan, a councillor in south Antrim, Northern Ireland, has joined other Irish politicians in calling for the closure of the plant.

They say discharges from the plant pose a threat to marine life in the Irish Sea.

The Irish government has been calling for a number of years for the closure of the Mox plant, and now Northern Ireland politicians are making a fact-finding visit.

Safety record

Mr Meehan said: "There are grave concerns regarding Sellafield, and its close proximity to Ireland.

"The people I represent have expressed their concerns about the high number of cancers and leukaemias that have arisen between the north and Republic of Ireland.

"We want to obtain more information before we arrive - but it is hard to come with an open mind when you know the safety record of Sellafield leaves a lot to be desired over the past years."

A spokesman for BNFL said: "We are pleased to welcome members of the Northern Ireland Local Government Association on a fact-finding visit to our site.

New fuel

"The delegation will tour some of the main facilities on the site that are of special interest to the visitors from Northern Ireland.

"They will meet with representatives of the workforce and site management as well as representatives of the local community in Cumbria to discuss issues of concern."

The Mox plant turns nuclear fuel already "burnt" in a reactor into a new fuel source, but creates new waste.

There are also fears that the mox plant could be the target of a terrorist action.