The BBC's Hugh Muir: "The Lawrence inquiry motivated the force to act against racism"

The plan is to use undercover black officers to test whether white officers are racist. Other measures include tempting officers with bribes.

Undercover officers already check on colleagues suspected of abusing their positions or breaking the law. Now these tests will be random to nip corruption and racism in the bud.

Sir Paul: Creator of a "ghost squad"

This is the latest phase of an ongoing investigation into corruption in the Met which has already seen more than 50 officers suspended and 20 charged.

In trial tests, marked banknotes were left in a police station with hidden cameras set up to record the results.

Members of the so-called "ghost squad" set up by the Met's Commissioner Sir Paul Condon also offered bribes to colleagues to test their honesty and to see if they reported the incident.

The squad plans to unmask racist officers by seeing how they react to planted racist remarks.

A senior source at Scotland Yard said the Met wants to clean up its image once and for all. "We believe we will then have in place the most comprehensive anti-corruption strategy of any police force in the world," said the source.

"Too often the police service has just waited for bad news to emerge. If you don't look for it, you won't find it."

Atmosphere of suspicion

The Police Federation's Metropolitan branch welcomed moves to stamp out corrupt and racist officers but expressed concern about creating an atmosphere of suspicion in the force.

"We've got 800 plus officers from the ethnic communities in the Metropolitan police service," said Glen Smyth of the Federation. "I'm sure that it wouldn't do one single one of those officers any good if their colleagues were wondering what were their motives in the talking to them," he said.

Black officers are just as worried about the effect on them.

Inspector Paul Wilson of the Black Police Association told BBC Newsroom South-East: "What this latest initiative may well do in fact is marginalise them because white officers will become suspicious, perhaps, of all black officers not knowing whether or not they've been planted."