A TERROR suspect accused of deliberately crashing a car outside the Houses of Parliament was not known to police or MI5, Scotland Yard has said.

The man, in his late twenties, is being held in custody at a south London police station but is not co-operating with officers, counter-terrorism head Neil Basu said.

He was arrested on suspicion of terror offences after the silver Ford Fiesta he was driving collided with cyclists and pedestrians before crashing into security barriers just before 7.40am on Tuesday.

Mr Basu said: "Given that this appears to be a deliberate act, the method and this being an iconic site, we are treating it as a terrorist incident and the investigation is being led by officers from the counter-terrorism command."

"We have not formally identified him yet. On the details we have at the moment we don't believe this individual was known to MI5 or counter-terror police."

The silver car can be seen coming along the road next to Parliament Square before moving to turn right towards Westminster Abbey in footage of the incident aired on BBC News.

As an ambulance passes the car on its right-hand side, the vehicle swerves left, crossing oncoming traffic and a pavement before entering a small road and crashing into a security barrier.

A police officer can be seen jumping another barrier that runs along the side of the road to get away.

Two white vehicles appear to be behind the car shortly before the crash but Mr Basu insisted: "There was not a police car in pursuit of the vehicle."

Images posted to social media showed a man wearing a black puffer jacket being led away in handcuffs from the car.

There was nobody else in the vehicle and no weapons were found, police said.

Mr Basu added no other suspects have been identified and there is "no intelligence at this time of further danger" to Londoners.

Two people were taken to hospital, while a third person with minor injuries was assessed at the scene, the London Ambulance Service (LAS) said.

One was discharged from St Thomas' Hospital before midday, while a woman is being treated for serious but not life-threatening injuries at St Mary's Hospital.

Prime Minister Theresa May said her thoughts were with those injured and thanked the emergency services for their "immediate and courageous" response.

A meeting of the Government's emergency cobra committee will be held at 2pm.