The police watchdog is investigating claims that one of Britain's most senior policemen met an undercover officer who spied on Stephen Lawrence's family.

The Independent Police Complaints Commission said it had started an investigation into allegations of "discreditable conduct and breaches of honesty and integrity" on the part of Metropolitan Police commander Richard Walton.

He was temporarily removed from his job as head of the counter-terrorism command SO15 in March following the publication of Mark Ellison QC's report into the original Lawrence murder investigation.

He revealed an undercover officer met Mr Walton, who was on Scotland Yard's Lawrence review team, in 1998. The IPCC will also investigate allegations of discreditable conduct by ex-officers, Robert Lambert and Colin Black.