One of the four men arrested in London last Friday on suspicion of a terrorist plot to buy radioactive material has been released without charge.
The three other men are being held at Paddington Green station
The man had been arrested at a Brent Cross hotel following a tip-off from the News Of The World newspaper.
The other three men are still being held at Paddington Green police station in central London.
They were arrested on suspicion of commissioning, preparing or instigating acts of terrorism.
The men can be held for a total of 14 days without charge.
The News Of The World claimed it sent in an undercover reporter posing as a "Muslim extremist" following a tip-off that a Saudi sympathetic to "the Muslim cause" was willing
to pay £300,000 for a kilo of powerful, radioactive "red mercury".
The chemical is said to have been developed by Russian scientists for "briefcase nuclear bombs", although scientists are divided over whether any
According to the News of the World, meetings were held with men
hoping to supply the radioactive material to their Middle Eastern buyer.
Police are believed not to have found any radioactive or bomb-making material.