A British customs official speaking to The Indian Express confirmed that they had intercepted cargo which included a substantial quantity of high-grade aluminium commonly used in making nuclear weapons. The official refused to comment on whether the cargo contained other components for nuclear weapons.

The confiscated cargo of 20 tonne of high-grade aluminium, is said to have originated in the US, according to The Sunday Express newspaper. It was tracked to the Thames port container terminal on the Isle of Grain, Kent, in the south-east of England in May.

The cargo was confiscated by UK customs, on May 20, before it could be transferred to a shipbound for the Middle East from where, it is thought, it would have travelled to Karachi.

Three men of Pakistani origin were arrested last week, by Britain's National Investigation Service, in connection with the incident. They are said to be linked to an import-export company based in west London which arranged the shipment. They have been bailed for two months awaiting the results of a UK Customs investigation into the incident.

Suspicions about the intended use and final destination of the shipment were aroused because the cargo was of such a high grade that it was likely to have been for military use than commercial. Although high-tensile aluminium may have normal commercial use, it is used for making missile casings and is also a component in solid missile propellant fuel. It is said to be essential for the construction of centrifuges used to enrich uranium for nuclear warheads.

The cargo was intercepted apparently because it did not have the correct paperwork. Under UK law, the export of certainmaterials that have a `dual use' -- both a commercial and military use -- require a special export licence. High-grade aluminium is such material. It is also on a so-called `trigger list' used by governments, including the UK, which have pledged to monitor the export of materials that aid the proliferation of nuclear weapons.

UK customs said that no other details of the case would be available until their investigation had been completed.

The Sunday Express, which uncovered the case, said that British and US intelligence officials monitoring nuclear proliferation activity alerted UK custom's officials about the shipment.