A second man has been arrested over a suspected terrorist attack outside Buckingham Palace, during which police were attacked by a man armed with a sword.

A 30-year-old man was apprehended by officers at an address in west London on Sunday morning, Scotland Yard said. Police are carrying out a search in the area, Metropolitan police reported.

A 26-year-old arrested at the scene remains in custody after a warrant for his detention until Sept. 1 was granted, the police said.