Mr Menezes was shot dead at Stockwell Tube station

The Metropolitan Police commissioner told the CBI conference in London the IPCC investigation was part of the "accountability" of the police force.

Mr Menezes' family says Sir Ian "misled" the public after police shot the electrician dead on 22 July.

Sir Ian also said police had foiled two further terrorist plots since the 7 July London bombings.

"We have disrupted two further terrorist conspiracies since July and charges have been drawn up," he said.

I see that [inquiry] as a proper part of my service's accountability and openness to scrutiny Sir Ian Blair

"The likelihood of further attempts is manifest. One of our great issues is that July was not a train crash, it is not part of normal life."

The Independent Police Complaints Commission inquiry into Sir Ian's handling of the aftermath of Mr Menezes' shooting was announced on Monday.

Sir Ian told the CBI conference on Tuesday: "I see that [inquiry] as a proper part of my service's accountability and openness to scrutiny, part both of our public duty and of the opening of the police to public engagement."

Early reports suggested Mr Menezes, 27, fled from London anti-terror officers.

He was shot eight times, seven in the head, at Stockwell Tube station after officers mistook him for a suicide bomb suspect.

Police suspicions

On the day of the shooting, Sir Ian told a news conference that, as far as he understood, the man shot dead had been directly linked to the anti-terrorist operation following the failed suicide bomb attacks on London the day before.

Scotland Yard was also quoted as saying Mr Menezes' "clothing and behaviour" added to suspicions he was a suspected suicide bomber.

The Menezes family lodged an official complaint alleging that Sir Ian and other senior officers made false public statements following the shooting.

Home secretary approval is required for an investigation into the commissioner of the Metropolitan Police.

Police reaction

On Monday, Deputy Assistant Commissioner John Yates issued a statement on behalf of the Met.

He said: "The Metropolitan Police welcomes the appointment of an investigating officer to consider these further complaints raised by the family of Jean Charles de Menezes."

He added that "all of those involved" would "co-operate fully" with the investigation.

Regarding inaccuracies widely reported in the aftermath of the shooting, the Met said a private apology had been made to Mr Menezes' family 48 hours after the shooting.

The statement said the police did not correct inaccurate information already in the public domain because the IPCC had "asked all parties involved not to comment once their investigation started".

'Impartial' truth

The de Menezes family welcomed the inquiry.

Mr Menezes' cousin Alez Pereira said: "This is fantastic news and a great victory for our campaign."

The Independent Police Complaints Commission probe will be led by senior investigator Mike Grant, and be separate from the IPCC's existing investigation into the circumstances of the shooting.

IPCC chairman Nick Hardwick said: "We have not made any assumptions and for the sake of Jean Charles' family, officers within the MPS and the public at large, will try to establish the truth in an impartial, proportionate and timely way."

A second aspect of the Menezes family's complaint - that Scotland Yard delayed informing it of the death - will be incorporated into the main IPCC inquiry expected to conclude by the end of the year.