Around 120 anti-nuclear protestors targeted roads leading to the plant.

The two-and-a-half-hour demonstration caused traffic congestion and six mile tailbacks.

The protest, which started at 6am, caused major delays on the A595.

A Cumbria Police spokesman told Ananova: "Five people have been arrested for obstruction.

"About 120 people took part. Some are believed to be from Ireland. The roads have now been cleared."

A spokesman for the plant's owner, British Nuclear Fuels Limited, said demonstrations were held outside at least two entrances.

A BNFL spokesman said: "BNFL respects the rights of any group that wishes to protest, providing these protests are peaceful, and do not threaten the safety of the Sellafield site or workforce.

"These protests have not disrupted the normal operations at Sellafield and business is continuing as usual.

"However by blocking the area's only major road the protestors have caused unnecessary and pointless inconvenience to the people, businesses and public services of West Cumbria