The Metropolitan Police Complaints Investigations Bureau, which examines accusations of police wrongdoing, launched its inquiry in July after being contacted by Sir Nicholas Lyell, the Attorney General. The allegations were made by Lord Spens, 52, a defendant in the Guinness case.
News of the CIB inquiry came the day after the Independent revealed that the SFO is carrying out an investigation into claims that its staff were guilty of misconduct during the inquiry into the Polly Peck tycoon, Asil Nadir. There is growing pressure for the SFO to be reformed or abolished.
The CIB is investigating the actions of Metropolitan Police officers who were seconded to the SFO to work with government lawyers and accountants on the Guinness case. The complaints involve the second Guinness trial, in which two men were charged with fraud and false accounting during the 1986 takeover battle for Distillers. The case collapsed in February 1992.
Lord Spens claims that up to 16 almost identical statements were prepared by the police and presented to potential witnesses for signature, although they were able to make alterations. He also claims that a paragraph in a scientific report on a tape recording of his co-defendant Roger Seelig was removed. It allegedly revealed that the recording could not be authenticated.
His third complaint was that the report of a government tribunal, that would allegedly have helped to vindicate him, was withheld from the defence for more than two years. It was finally released on Christmas eve - less than two months later the case was dropped.
Lord Spens said: ``At the SFO they seem to believe that the end justifies the means. They appear to be answerable to no one.'' He first made the allegations to the Lord Chancellor in July last year.
A Scotland Yard spokesman said last night: ``A complaint was received and the director of CIB authorised an investigation to take place. Nothing has so far come to light which renders any police officers liable to be disciplined.''
George Staple, the SFO director, said last night: ``I believe we have a very good record. People do continually question the way the SFO functions - I think much of it is unfair.''
In a letter to the Independent he confirmed that the SFO, along with two senior officers from other government departments, was investigating the actions of SFO staff involved in the Nadir inquiry.
He said they will be examining allegations that ``privileged'' documents were passed on to the prosecution against the will of the defence. The outcome of the investigation would not alter the Crown's case against Nadir.
Michael Mates, the former Tory minister who resigned over the Nadir affair, confirmed yesterday that he had been in correspondence with the Attorney General over the allegations. He also made it clear that he had not received any gifts or other favours from Nadir and said his interest in the case was prompted solely by his concern over the conduct of SFO officials.
Leading article, letter, page 15