Two men have been arrested by armed officers over a suspected terror plot after they were seen acting suspiciously in the Westminster area, police said.

The pair, who are both aged 34 and from east London, were held in Pall Mall, which connects Trafalgar Square to St James's Street, shortly after midnight on Thursday.

Officers searched both of the men and the vehicle, but no firearms were discharged, the Metropolitan Police said.

The men were arrested on suspicion of preparation of terrorist acts, contrary to section five of the Terrorism Act 2006, and are being held in custody at a central London police station.

Scotland Yard said they were stopped and arrested at around 12.10am on Thursday by armed officers after they were seen acting suspiciously in a car in the Westminster area.

Commander Richard Smith, head of the Met Police counter terrorism command, said: "Every day, police officers are on patrol across the capital, watching for suspicious behaviour and stopping people they suspect may be involved in criminality.

"The public can help us continue to keep London safe by being vigilant and reporting any suspicious behaviour to police.

"Following the increase to the UK threat level from terrorism last week - as a precautionary measure in response to recent events in France and Austria - I would like to emphasise that the public should be alert but not alarmed."

The Met's counter-terror unit are leading the investigation.