Police say street crime has been reduced

The two-week initiative is part of Operation Safer Streets which was first introduced in February 2001.

The Metropolitan Police say about 50% of all street crime involves mobile phones and they should be kept out of sight in crime hotspots like train and Tube stations.

The message "Out of sight is safer" will appear on posters on trains and buses, at stations and in high streets.

Assistant Commissioner Tim Godwin said the public had a role to play in reducing crime.

"The message is simple: keep valuables out of sight whenever possible, especially at crime hotspots like Tube and train stations.

"When you do have to take your phone or cash out in a public place, be aware of who's around you. Street robbers tend to be opportunistic - don't make yourself an easy target."

Operation Safer Streets was first introduced in nine boroughs but later became London-wide.

The Met claims it has brought street crime down from 7,000 reported offences a month in late 2001 to about 5,000 in 2002 and 2003.