A man armed with several knives has been arrested in Whitehall on suspicion of planning a terror attack, Scotland Yard said.

The suspect was carrying a rucksack containing at least three knives when he was detained "following a stop and search as part of an ongoing operation", police said.

Forensic Officers looking at with knives at the scene after a man was arrested following an incident in Whitehall in London

The Metropolitan Police said in a statement that he was held at approximately 2.22pm on Thursday by armed officers from the Specialist Firearms Command.

It went on: "The man, aged in his late twenties, was arrested on suspicion of possession of an offensive weapon and on suspicion of the commission, preparation and instigation of acts of terrorism.

"Knives have been recovered from him.

Armed police talk to man at the scene after a person was arrested following an incident in Whitehall in London

"He is being detained under the Terrorism Act and is in custody in a south London police station.

"Detectives from the Counter Terrorism Command are continuing their investigation, and as a result of this arrest there is no immediate known threat."