The St Petersburg metro attack suspect has handed himself in to police - but denies planting the nail bomb on the train which killed 11 people and injured 50 today. 

Several Russian media outlets released the CCTV pictures of the bearded suspect, who was wearing a long, black top and a hat, blamed for causing the carnage by detonating a bomb that was packed with shrapnel while it was travelling between Sennaya Ploshchad and Sadovaya metro stations. 

A second explosive device disguised as a fire extinguisher was found and defused in a nearby station and police issued a search warrant for two suspected terrorists.

Tonight, it has emerged that the bearded man who was identified on CCTV as the main suspect, handed himself in to police and insists he is innocent.

Russian authorities are also probing the possibility of a suicide bomber being involved - described as a 'young man from Central Asia'.