NEVILLE Lawrence has demanded a full public inquiry into the "horrific" allegations Scotland Yard sought to smear him and his family as they campaigned for justice in the wake of the racist murder of his son Stephen.

His call was echoed by MPs, who suggested the public had had enough of the police investigating the police and there should now be a full independent probe into the use of undercover operations by the Metropolitan Police.

An initial report into how undercover officers used the identity of dead babies is due to be published before the end of July.

As Theresa May, the Home Secretary, used an emergency Commons statement to announce two parallel inquiries – one by a QC and another by the police – into the latest allegations of a covert smear operation by Scotland Yard, Mr Lawrence insisted this was totally unsatisfactory.

He said: "Nothing short of a judge-led public inquiry will suffice and I have no confidence the measures announced today will get to the bottom of this matter."

His ex-wife Doreen, who endured years of heartache at the lack of progress in convicting her son's killers, said the latest revelations were the worst of all.

David Cameron expressed his dismay, saying: "These are absolutely dreadful allegations and we can only think of the Lawrence family, who have suffered so much already from the loss of their son.

"To hear that, potentially, the police who were meant to be helping them were actually undermining them –that's horrific."

The Prime Minister pledged to reach "the full truth".

London mayor Boris Johnson condemned as "utterly disgraceful" the activities described by undercover officer Peter Francis, who claimed he was put under pressure from his superiors to dig up "dirt" shortly after Stephen Lawrence, an 18-year-old architecture student, died. He was killed in an unprovoked racist attack in April 1993 as he waited for a bus in Eltham, south-east London.

Mr Francis said he was also asked to target Mr Lawrence's friend Duwayne Brooks, who witnessed the murder, and other campaigners angry at the failure to bring his killers to justice.

Scotland Yard said it was "not prepared to confirm or deny" the truth of Mr Francis's claims.

Lord Condon, who was commissioner from 1993 to 2000, insisted he was unaware of any order to smear the Lawrence family, saying: "I am shocked and dismayed by the allegations made by the former undercover police officer Peter Francis."

Sir Bernard Hogan-Howe, the current Commissioner, said he too was "personally shocked" by Mr Francis's claims, stressing: "If these allegations are true, it's a disgrace and the Met will apologise. Smearing the family of a murder victim would never be acceptable to me or my officers."

In 1999, Sir William Macpherson headed a public inquiry into the original police probe into the Lawrence murder and concluded it had been "marred by a combination of professional incompetence, institutional racism and a failure of leadership by senior officers".

In the Commons yesterday, Ms May told MPs the smear claims would be investigated by QC Mark Ellison, who led the prosecution of Gary Dobson and David Norris. They were convicted of Mr Lawrence's murder in January 2012.

Clive Efford, the Labour MP for Eltham, said: "People are not satisfied with the police investigating the police."