The Environment Agency has ruled that a shipment of nuclear Mox fuel due to be returned to the UK from Japan is not radioactive waste.

The decision means that British Nuclear Fuels (BNFL) does not need special authorisation for the cargo, as Greenpeace has claimed.

I'm not surprised to hear that Greenpeace is likely to challenge this

Environmental Agency chairman Sir John Harman

The environmental group says it will ask the High Court for a judicial review of the decision to try to block the shipment.

The Mox fuel was sent to Japan in 1999 for use at a reactor site, but rejected because Japanese authorities were concerned about the falsification of quality-control data by BNFL.

The controversial fuel, which Greenpeace calls "faulty, rejected plutonium", is due to be sent to Sellafield's Mox plant in Cumbria later this week.

Speaking on BBC Radio 4's Today programme, Greenpeace's chief scientist Doug Parr said his group was challenging the decision in court.

But he added that the legal system seemed stacked in the nuclear industry's favour.

"Matters like the fact that this is the first plutonium-based shipment to go on the high seas since September 11th doesn't seem to be a legal way of challenging the ruling," he said.

Protesters have regularly targeted Sellafield

Environment Agency chairman Sir John Harman defended the ruling, but welcomed a court challenge.

"I'm not surprised to hear that Greenpeace is likely to challenge this," he told the Today programme.

He said security concerns about the shipment were not considered in the agency's decision and is covered by other regulations.

"If we had said it was waste, and it needed to obey, so to speak, the transfrontier shipment rules, it's hard to see how the security measures could have been very much greater," he said.

Foreseen use

The ruling hinged on whether Mox fuel, which is short for mixed oxide plutonium/uranium, had any foreseen use. If it did, it could not be classified as waste.

Mr Parr argued that the fuel should not be classified as useful, since BNFL plans to extract plutonium from it - something he said the UK already had too much of.

A statement from the Environment Agency said the fuel would be loaded on to two ships and sent to the UK from Japan soon.