Police in Britain are questioning four men under anti-terrorism legislation after a tip-off from a newspaper which said the suspects tried to buy explosives for a dirty bomb.
Three of the men were arrested at a hotel in Brent Cross, north London, on Friday. The fourth was seized later the same day at his home, also in north London.
"All four were arrested under section 41 of the Terrorism Act, on suspicion of the commission, preparation or instigation of acts of terrorism," London police said in a statement.
"The men remain in custody at present," a police spokeswoman said today.
Police said they acted on information provided by the
News of the Worldnewspaper, which said one of its reporters had infiltrated a gang trying to buy radioactive material for a Saudi Arabian who it said might be linked to al Qaeda.
The tabloid newspaper said the Saudi was prepared to pay £300,000 (€441,807) for a kilogramme of 'red mercury', a mysterious radioactive substance which is said to have been developed by Russian scientists during the Cold War.
The paper said one of its reporters made contact with an Indian-born banker and a Somali - the head of the gang - who wanted to buy bomb-making material for a client in the Middle East who they said supported "the Muslim cause".
Under terrorism laws, suspects can remain in custody without charge for 14 days.