British police said they have arrested four men in London on suspicion of ordering, planning or trying to carry out a terror attack.
The arrests were made in a series of pre-dawn raids on Tuesday in the southwest of the capital, said a spokeswoman for London's Metropolitan Police. Security sources said the arrests were linked to international terrorism.
The suspects were being questioned at a central London police station.
"Four men - two aged 29, one aged 28 and one aged 32 - were arrested under section 41 of the terrorism act 2000 on suspicion of involvement in the commission, preparation or instigation of acts of terrorism," the spokeswoman said.
Britain has been on its second-highest security alert for two weeks after intelligence officials said they had information that an attack was planned, without specifying any target.
On Monday, Britain's anti-terror police were granted two more days to question a suspected would-be suicide bomber arrested in the southwestern town of Gloucester last Thursday.
