Man with knife arrested near Buckingham Palace

A man carrying a knife was on Wednesday arrested near Buckingham Palace in London as Britain raised its terror threat level to "critical" after the Manchester terror strike that killed 22 people.

The man was detained on The Mall, the street that leads up to the Palace, after Metropolitan Police officers on patrol in the area stopped and searched him. Patrolling officers detained and searched a man in The Mall. A knife was recovered and the man was arrested on suspicion of a possession of an offensive weapon. He has been taken into custody at a central London police station. The incident is not believed to be terrorism related, a Met Police statement said.

The arrest came as the British capital went on high alert, with many of its prominent landmarks including the Palace, Downing Street and Houses of Parliament under additional security in the wake of the suicide bombing at an Ariana Grande concert in Manchester on Monday night.

The Met Police said it has increased police numbers and operations across London with immediate effect as Army troops arrived in the city as part of Operation Temperer.