Armed British police have arrested a man in connection with preparing a terror attack just yards from Downing Street in London.

Officers shut down the roads around Whitehall as they carried out the arrest, pushing the man to the ground before holding him at the scene.

The man, who was carrying a bag of knives, was arrested in Parliament Street - close to the scene of last month's terror attack which killed five people.

Forensic officers were seen examining a bag of knives on the pavement at Whitehall while policemen held the man nearby.

Reporter Lewis Goodall said: "A witness said at one point he was taken to the ground - he was wearing a black tracksuit. Police surrounded him.

"There are various police officers here, both armed guards and forensic officers who are examining the scene. Earlier, we managed to get in the thick of it and we could see a bag clearly with a selection of knives which are being examined.

"This is one of the busiest thoroughfares in London, you've got thousands and thousands of people working in Government departments among other things and the area has come to something of a standstill."