Technology which can detect whether people are carrying hidden weapons will be used by police for the first time in a London train station in a bid to tackle knife crime.
The five-day trial of the new equipment began in Stratford train station, east London, on Monday, the Home Office said.
The technology - already in use on the Los Angeles Metro - has been developed to spot weapons like guns, knives and explosive devices concealed under clothing at distances of up to 30ft by looking for objects that block a person's body heat.
The Home Office has spent around £40,000 on the scheme which is being used by British Transport and Metropolitan Police officers.
The trial will look at how officers can use technology to find weapons without having to stop the individual or get them to empty their pockets and if it would be effective in the battle against knife crime.
The technology allows police officers to see the size, shape and location of any concealed item. It does not show any intimate body parts and it is impossible to tell an individual's gender, age or ethnicity from the imagery it produces, the Home Office said.