Dizaei was tipped to be the UK's first ethnic minority chief constable

Superintendent Ali Dizaei was suspended from his �52,000-a-year job two years ago amid allegations of drug dealing and using prostitutes.

But he never faced charges relating to those allegations and, despite a four-year investigation, the high-ranking officer was cleared of dishonesty, while charges of fiddling expenses were dropped.

Now, following the break down of talks to reinstate Mr Dizaei, the National Black Police Association (NBPA) has called for a boycott of black and Asian recruits to London's police force.

The Met's assistant commissioner in charge of human resources, Bernard Howe, said the force was "extremely concerned" about the boycott.

We have set up an inquiry in London to examine all the issues relating to the way Met procedures operate Toby Harris Metropolitan Police Authority chairman

The force, which has defended its handling of the case, needed "ethnic minority officers for the benefit of all", he added.

"Anything that stops that is not in the best interests of Londoners."

The Met has to recruit about 8% of its force from the ethnic minorities by 2009.

Mr Dizaei, from Henley-on-Thames, Oxfordshire, was suspended in 2001 amid allegations of drug dealing and involvement with prostitutes.

But after a four-year investigation, all charges against Mr Dizaei were dropped.

National Black Police Association (NBPA) president Ray Powell said he was bitterly disappointed at the collapse of talks about Mr Dizaei's reinstatement.

This cannot be good for the Metropolitan Police and certainly it is not good for me and my family Ali Dizaei Met officers 'spread racism'

He told BBC Radio 4's Today programme there had been "several attempts to put an end to this fiasco in the interests of the police service and the wider community".

But the NBPA could no longer encourage black and Asian recruits to join a force that had openly and persistently discriminated against its staff, officers and the community, he said.

The NBPA is also calling for the suspension of senior officers involved in the investigation into Mr Dizaei.

Mr Dizaei told BBC News he was "very sad" and disappointed the talks had collapsed.

"This cannot be good for the Metropolitan Police and certainly it is not good for me and my family," said Mr Dizaei, who is supporting the boycott.

I think the NBPA is blackmailing the Met police to do something which needs to be done by way of an inquiry Mahesh Nhanda, Metropolitan Police Hindu Association Dismay at boycott call

In September, when he was cleared, Mr Dizaei, one of the force's most senior ethnic minority officers, said he had been the victim of a "witch hunt" because of his outspoken views on racism in the force.

Second-in-command at west London's Kensington police station, he had been tipped to become the UK's first ethnic minority chief constable.

On Wednesday Police Superintendents' Association deputy secretary Chief Superintendent Philip Aspey said Mr Dizaei wanted to rebuild his career in London.

"He was never seeking special treatment, just fairness like any other officer returning to work following a period of suspension."

Hundreds of black and Asian officers and police civilian workers from across the UK are to march on Scotland Yard in full uniform on 17 November to call for the Met "and other forces who behave in this manner" to be investigated.

Inquiry launched

NBPA spokesman Clive Morris told BBC News Online "brothers" from black police associations in the United States and South Africa would join the march.

The NBPA says black and Asian officers and police civilian workers are five times more likely to be disciplined.

Metropolitan Police Authority chairman Toby Harris, an Association of Police Authorities executive member, told the Guardian: "We have set up an inquiry in London to examine all the issues relating to the way Met procedures operate."

But Nottingham Black Police Association deputy chairman Glen Williams told the newspaper Mr Dizaei's case was not a "one-off".

"In Nottingham we had the case of Surinder Singh, an officer who went to a tribunal and proved he had been unfairly treated because of his race.

"It is happening all over the country."