Portable scanners are being used to screen passengers from up to 30ft away without them having to pass through a security checkpoint.

The Home Office said the scheme was part of a "battle against knife crime".

Policing Minister Kit Malthouse said: "No-one should feel they can walk the streets with a knife and expect to get away with it.

"We are pulling out all the stops in a battle against knife crime in London and across the country."

The scanners, built by British firm Thruvision, reveal objects hidden inside clothing that block body heat.

Sensitive cameras capable of screening 2,000 passengers an hour will enable officers to see the size, shape and location of any blade or gun.

It does not show any intimate body parts, the Home Office said.

The station, which connects several Transport for London lines with Overground services, has an average of 110,000 passengers a day.

The trial will also look at how officers can use technology to reduce reliance on controversial stop-and-search powers.

Thruvision is already used on the Los Angeles Metro, which last year became the first mass transport system in the US to adopt it.

Assistant Chief Constable Robin Smith, from British Transport Police, said: "Fortunately, knife crime on the rail network is very low.

"In support of the Home Office and other police forces, we are keen to explore how technology can assist us in tackling violent crime head on."