POLICE are urging commuters "to remain alert" and foil terrorist activity.

Posters will be displayed on bus shelters and in stations asking the public to be vigilant and to report suspicious bags or behaviour by calling 999.

The drive is a partnership between British Transport Police, City of London Police, Transport for London and the Mayor's Office.

Head of the Met's Anti-Terrorist Branch deputy assistant commissioner Peter Clarke said: "Everyone who lives in London or visits for work or pleasure has a role to play. We can't afford to be complacent."

Call the anti-terrorist hotline on 0800 789321.