Scotland Yard has urged people to remain vigilant after a fifth person was stabbed in north London right under the noses of a police patrol.

A man in his 30s was left in critical condition after being knifed in the back just yards from the scene of a previous incident, prompting fears the attacker could be taunting the police.

It was the fifth knife attack in the area since Saturday evening, in a spree that has left three people critically ill.

A man in his 30s was arrested in connection with the attacks on Tuesday morning, but police have warned people to remain on their guard in case the person responsible is still at large.

Another suspect who was arrested on Sunday remained in custody last night after police were given more time to question him, while a third suspect was bailed by police.

The spate of stabbings has led to widespread concern in the local community, with schools put into lockdown and children warned not to walk home alone.