Children as young as eight who put their lives at risk will be targeted in a crackdown on crime and vandalism on London Underground. British Transport Police said it will track down people who throw objects at Tube trains, trespass on lines or vandalise railway equipment.
A police helicopter will patrol the network throughout Easter using sophisticated camera equipment.
Police warned trespassing was dangerous and a criminal offence.
Meanwhile, members of train drivers' union Aslef are being balloted for strike action after bricks were thrown at trains at the eastern end of the District Line.