One of the country’s most senior police officers is being investigated for alleged misconduct amid allegations that he advised a defence team on how to undermine a criminal case brought by his employer.

Commander Ali Dizaei, the President of the National Black Police Association, is alleged to have acted as a consultant to point out weaknesses in a case brought by the Met police against a woman accused of leaving the scene of a fatal hit-and-run.

Mr Dizaei completely denies the accusations and has told The Times that he will be looking “at all his legal options” once the investigation is over.

The investigation started after a complaint was made directly to Sir Ian Blair, the Metropolitan Police Commissioner, more than a month ago. He referred the matter to the Directorate of Professional Standards, the Met’s internal investigations team.

They in turn referred it to the Metropolitan Police Authority, which appointed Deputy Chief Constable Phil Gormley, from the West Midlands police force, to head the investigation. Mr Gormley worked with Mr Dizaei at Thames Valley Police.

The matter was also referred to the Independent Police Complaints Commission (IPPC) because it is a potential conduct matter, which decided that it could be investigated by the Metropolitan Police Authority.

The Times understands that Mr Dizaei asked the police authority for a personal assurance that the decision to record “this malicious complaint” and refer it to the IPPC is unrelated to his role as the President of the Black Police Association and as the person representing Assistant Commissioner Tarique Ghaffur, who is alleging race discrimination against Sir Ian and key members of the Met.

In a letter sent last month the police authority assured Mr Dizaei that the decision had “absolutely no connection” with his role at the Black Police Association or his involvement with Mr Ghaffur.

A spokesman for the Metropolitan Police Authority said yesterday: “Commander Dizaei is being investigated by the MPA for a matter of alleged misconduct. The MPA has a statutory duty to investigate all allegations of misconduct and takes this responsibility very seriously.”

Mr Dizaei said: “I deny this allegation entirely. I have never been involved in this case at all, absolutely not. I never acted as a consultant against the Met.”

The investigation will add to the problems of the upper tiers of the Metropolitan Police. Sir Ian is also at the centre of an inquiry into allegations that he influenced the award of police contracts to a close friend. He denies the allegations.

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