Police are using hidden cameras to monitor the activity of people running illegal gaming scams on Westminster Bridge, according to Mayor of London Boris Johnson.
Mr Johnson was responding to a question from the Green Party London Assembly member Baroness Jones of Moulsecoomb.
"Westminster and Lambeth are currently running covert CCTV-supported operations with safer transport command colleagues targeting the gamblers on Westminster Bridge," said the Mayor.
Last October the police carried out a major operation on the bridge which resulted in 25 arrests. 18 people were charged and seven cautioned for relevant offences.
In addition, officers applied for six antisocial behaviour orders (ASBOs).
Mr Johnson added: "Westminster and Lambeth Borough Police, as well as safer transport officers, all regularly deploy plain clothed officers to patrol the bridge."