The investigation into alleged police attempts to smear the Stephen Lawrence campaign and undermine the credibility of witnesses attending the Macpherson inquiry into the black teenager’s racist murder is focusing on the activities of five forces, The Independent has learnt.

Investigators are understood to be waiting for senior officers from Avon and Somerset Constabulary and West Midlands Police to complete urgent trawls of their records in relation to possible surveillance or intelligence gathering operations carried out in Bristol and Birmingham.

The cities, alongside Bradford and Manchester, hosted regional sittings of the Macpherson Inquiry in 1998 where race relations campaigners aired a string of grievances against their local forces over stop and search and other flashpoint issues.

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The former Chief Constable of West Yorkshire Police, Sir Norman Bettison, who is already at the centre of an Independent Police Complaints Commission (IPCC) inquiry into an alleged cover-up in the wake of the Hillsborough disaster, was referred to the watchdog this week by Police and Crime Commissioner Mark Burns-Williamson.

It followed revelations that leading anti-racism campaigner Mohammed Amran was the subject of a potentially damaging special branch report prior to his giving evidence to the inquiry in Bradford. A number of junior officers from West Yorkshire are also being investigated by the IPCC after being referred by the present Chief Constable.

Greater Manchester Police has also been referred over an internal memo suggesting intelligence was gathered on individuals or groups attending the inquiry in the city.

The cases are likely to be reviewed by Mark Ellison QC - who successfully prosecuted Gary Dobson and David Norris for Stephen's murder in 2012 – as part of an investigation into the Metropolitan Police following claims of a smear campaign against the teenager's family and friends made by a former undercover officer.

The inquiry will need to uncover whether the regional forces were acting on behalf of the Met, which was embroiled in one of the biggest crises in its history following the repeated failings to investigate the student’s 1993 murder. It was eventually found to be “institutionally racist” by Macpherson.

West Midlands Police and Crime Commissioner Bob Jones met Chief Constable Chris Sims on Monday to discuss the issue. In a statement the force confirmed it was examining material to see whether any potentially inappropriate intelligence or surveillance activity had taken place.

A team of officers from Avon and Somerset Constabulary have now begun a second trawl of documents after the Home Secretary Theresa May ordered forces nationwide to search their records. A first hunt carried out by an assistant chief constable was said to have discovered no incriminating material. Forces have until next Wednesday to report their findings to Ms May.

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Mr Amran, 37, who became the youngest ever Commissioner for Racial Equality (CRE) following his role as a peacemaker in the 1995 Bradford riots, has been told he will not know for at least two weeks what evidence was gathered against him although it is not believed he was placed under surveillance.

His lawyer, Ruth Bundey, said: “He is someone who has helped and advised the authorities in the past and it is very disconcerting for him not to know what is involved here – other than to have been told that it is ‘alarming.’”

It is unclear whether evidence allegedly gathered about Mr Amran resurfaced in a further dossier put together by West Yorkshire Police as part of its alleged attempt to prevent him being re-elected by the CRE. The dossier led Ms Bundey to pursue a successful case of racial discrimination against the force, who settled out of court in 2002.

Mr Amran told The Independent that he was repeatedly arrested after publicly questioning the policing of in Bradford’s multi-racial community.

Despite widespread concern over policing and community relations leading up to the 1995 riots, more disturbances took place in the city in the summer of 2001.

“I challenged the police openly after the 1995 riots and that created a reaction that made my life very difficult,” Mr Amran said. "The arrest I remember most vividly came when I was going to my family home and three officers grabbed me and told me I was under arrest.

"They said ‘You should not be here.’ I was letting myself into my house at the time and they said ‘drop the keys. You are under arrest.’ I sustained a hairline fracture of my arm. They just let me go. On another occasion I was dragged from my car by police. I told them who I was and they didn’t believe me."