The new program, called Blunt 2, started this week in one borough and should be in place in all 32 London boroughs within the next few months, said a Metropolitan Police spokesman, who asked not to be identified in line with police rules.
The scanners have been in use by police for several years, but many more have been purchased and they will now be used much more aggressively under a law that gives police the right to search people without having to demonstrate beforehand that there is reasonable cause to believe they are committing a crime, the spokesman said.
"We've put it in under Section 60 of the Public Order Act, which is slightly more in your face," the spokesman said. "We can give officers on the ground the powers to go ahead and do it. We've got 550 metal detector wands and 244 search arches that can be used. If there's a problem, we can place them outside a row of shops or a shopping center and check people going in."