Police are investigating whether Tommy Sheridan's solicitor's phone was targeted by a hacker during preparations for the Scottish Socialist's perjury trial arising from his libel victory against the News of the World.
Aamer Anwar, who represented Sheridan throughout his legal fight with Rupert Murdoch's top-selling paper over stories about his sex life in 2005, said his mobile phone company warned him last June that an attempt had been made to access his mobile phone messages and change his password.
He reported the suspected hacking to Strathclyde Police a month ago, triggering an investigation.
According to Mr Anwar, the hacking came at a particularly sensitive time in the legal proceedings against Sheridan for giving false testimony during his successful defamation action against the NOTW in 2006 over claims he visited a swingers' club and had adulterous affairs.
During the perjury trial Sheridan, who was convicted and jailed for three years in January, claimed the NOTW's owner News International had set out to "destroy" him and had used the services of the private investigator Glenn Mulcaire to hack into his phone.
Mr Anwar, a human rights lawyer, is the third public figure to come forward with claims of being targeted by phone hackers in the past 24 months, long after the practice was exposed with the conviction in 2007 of Mr Mulcaire and former NOTW royal editor Clive Goodman for intercepting the messages of aides at Buckingham Palace.
Kelly Hoppen, the interior designer and step-mother of actress Sienna Miller, is suing the NOTW and one of its reporters, Dan Evans, for allegedly attempting to access her voicemail in 2009. The newspaper and Mr Evans, who claims "sticky keys" on his phone may have led to an apparent attempt to listen to messages, deny the claims.
Tessa Jowell, the former Labour cabinet minister, contacted Scotland Yard in January after receiving a warning from her mobile phone company that someone had tried and failed to access her voicemail messages.
Mr Anwar said the timing of the incident involving his mobile phone had coincided with pre-trial proceedings under the Scottish legal system called commission hearings, at which evidence to be heard in the full trial is presented, giving a clear indication of how both prosecutors and the defendant plan to conduct their cases. In particular, he was seeking disclosure from the Metropolitan Police and the NOTW of key documents relating to Mr Mulcaire and allegations that witnesses had received payments.
Mr Anwar said: "I received an alert from Vodafone saying there had been an attempt to hack my voicemail and change my PIN. I do not know who was responsible for this and the police are investigating. The incident happened at a time when we were still getting information about the documents that would be used against Mr Sheridan.
"If indeed my phone was hacked, then that obviously has important implications for the vital ability of a lawyer to speak to his or her client without being listened to."
There is no evidence about who might be responsible for the hacking. A Strathclyde Police spokeswoman said: "Inquiries are still ongoing in this matter."
The Independent understands that detectives are awaiting the transfer of phone records from Vodafone which will reveal the number used to make the suspected attempt to hack Mr Anwar's phone. The ability of detectives to identify any individuals linked with that phone will hinge on whether they used an untraceable pay-as-you-go handset, a so-called "burner".
Phone hacking was an important issue in the perjury trial because it emerged that details about Sheridan appeared on the notes of Mr Mulcaire, prompting Sheridan to claim he was the target of attempted hacking.
Detective Chief Superintendent Philip Williams, who led the original Scotland Yard investigation into Mr Mulcaire, confirmed that Sheridan's mobile phone number, address and two PIN codes appeared in the private detective's records but said there was no evidence that the information was used to access his voicemails.
Andy Coulson, the former editor of the NOTW who resigned twice over the hacking scandal by stepping down from the newspaper in 2007 and quitting as David Cameron's spokesman in January, told Sheridan's perjury trial that he had not ordered Mr Mulcaire to intercept the politician's messages. He said: "I had absolutely no knowledge of it and I certainly didn't instruct anyone to do it."
The Independent disclosed last month that the editor of the Scottish edition of the NOTW, Bob Bird, had given inaccurate evidence to the trial when he said that "lots of emails" between staff and executives at News International had been lost in a data transfer to India. News International has confirmed that all electronic records are stored safely in Britain. Police are expected to request access to the archive in efforts to discover the full extent of the scandal.