Image caption Stephen Lawrence was 18 when was he was killed in a racially-motivated attack

Claims of "discreditable conduct" by Metropolitan Police officers after the murder of teenager Stephen Lawrence are to be probed by the police watchdog.

The Independent Police Complaints Commission will examine the behaviour of the head of the Met's counter-terrorism unit Cdr Richard Walton.

It is alleged he got information from a police spy about the Lawrence family, "potentially undermining" the inquiry.

The IPCC will also look at the conduct of two former officers.

'IPCC teeth'

Imran Khan, a solicitor for Stephen's mother, Baroness Lawrence, said: "We believe that this is a strong test for the IPCC because they recently had to apologise to Mrs Lawrence for the failure of their investigation into corruption in 2006.

"What Mrs Lawrence now wants is a proper independent - with a capital "I" - investigation into this matter and results which show the IPCC has got teeth.

"I want to say to those in charge of the IPCC that Mrs Lawrence is looking at you with great scrutiny and you ought to do a better job than you did in 2006."

The watchdog said it would look at claims Mr Walton "met with an undercover officer and obtained information pertaining to the Lawrence family and their supporters, potentially undermining the inquiry and public confidence".

Stephen Lawrence murder Image copyright Other Image caption Stephen Lawrence was murdered in south-east London in 1993 Black teenager Stephen Lawrence, 18, was stabbed to death in an unprovoked attack by a gang of white youths as he waited at a bus stop in Eltham, south-east London, in April 1993. A number of suspects were identified soon after the attack but it took more than 18 years to bring his killers to justice. Several attempts to prosecute the suspects, including a private prosecution by the family, failed owing to unreliable or insufficient evidence. In 1997, then Home Secretary Jack Straw ordered a public inquiry into the killing and its aftermath after concerns about the way the police had handled the case. Sir William Macpherson, a retired High Court judge, led the inquiry. He accused the police of institutional racism and found a number of failings in how they had investigated the murder. In January 2012, Gary Dobson and David Norris were found guilty of the murder by an Old Bailey jury after a review of the forensic evidence. Stephen Lawrence murder: Timeline

It also said it would examine claims he provided "inconsistent accounts" to the Ellison review, which examined allegations of corruption surrounding the initial murder investigation.

Mr Walton 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.

The IPCC will also investigate the actions of former officer Det Insp Robert Lambert and Cdr Colin Black, who were both identified in the review as having played a part in setting up the meeting with the undercover officer.

The BBC's home affairs correspondent Matt Prodger said Mr Lambert was revealed in 2011 as being a member of the controversial Special Demonstrations Squad (SDS) undercover unit, and Mr Black is a former commander of Special Branch.

It follows claims the SDS spied on the Lawrence family to gather intelligence for the Met.

Mr Lambert said: "I will continue to co-operate with Operation Herne, the Ellison Review and will now co-operate with the IPCC investigation announced today."

IPCC deputy chairwoman Sarah Green said: "Mark Ellison's review highlighted a number of extremely serious matters which strike at the heart of public confidence in the police.

"Following the review, I asked the Met Police to consider whether the conduct of any officers or former officers should be recorded and referred to the IPCC.

"Having now received referrals in relation to all three of the above officers, and in view of the seriousness of the matter and the significant public interest, I have determined the IPCC should conduct an independent investigation."

Media playback is unsupported on your device Media caption Doreen Lawrence's solicitor Imran Khan: "We always wanted action to be taken"

Speaking from his home in Jamaica, Stephen's father Neville Lawrence said: "It's a welcome step and I hope the investigation is thorough and gets to the truth.

"But this relates to one small part of the Ellison report. I remain concerned that the Metropolitan Police did not fully co-operate with the Macpherson inquiry and I do not want this issue to be swept under the carpet.

"I will be making a complaint to the IPCC about this. My family and I have to go through another public inquiry and I want to do everything I can to make sure that the police know that they have to be open and transparent during that inquiry."

Stephen was 18 when he was stabbed to death in an unprovoked attack by a gang of white youths in Eltham, south-east London, in April 1993.

In 2012 Gary Dobson and David Norris were found guilty of murdering him and sentenced to minimum terms of 15 years and two months and 14 years and three months respectively.