One of Britain's most senior police officers is stepping into the public spotlight to make a series of explosive allegations against his force.

Assistant Commissioner Tarique Ghaffur will accuse senior colleagues within Scotland Yard of a racist campaign designed to undermine his authority.

Among those facing highly-damaging allegations are Commissioner Sir Ian Blair and Metropolitan Police Authority chairman Len Duvall.

Mr Ghaffur will address reporters just days after his solicitors filed an employment tribunal claim against the Metropolitan Police.

The senior officer, who is responsible for security preparations for the 2012 Olympics, is thought to be claiming a seven-figure sum in lost earnings and damages.

Details of a dossier of evidence compiled by Mr Ghaffur since 2000 and a rift between him and Sir Ian were leaked in June.

Colleagues said evidence of bullying, discrimination and victimisation against the senior Asian officer is compelling.

Attempts to head off a full-scale employment tribunal with mediation failed after the two parties could not even agree the terms for talks.

The press conference at a central London hotel will be the first time Mr Ghaffur has spoken in public about the row. It will also be the first opportunity for Sir Ian to hear the case against him as the tribunal dossier is yet to be sent on to his force.

Sir Ian and Mr Duvall strongly rejected claims of racism. Sir Ian said he has a long and honourable record for championing diversity.