Two men have been arrested on suspicion of terrorism offences after their car was stopped along Pall Mall in central London, police have said.
The pair, both 34 and from east London, were spotted acting suspiciously in a car in Westminster at around 12.10am on Thursday and were stopped by armed officers in Pall Mall, the Metropolitan Police said.
They were arrested under the Terrorism Act and taken to a police station where they are still being held.
No guns were fired and a counter-terror investigation has been launched, the force added.