Police are investigating a complaint from Scottish politician Tommy Sheridan that he has been bugged.
Tommy Sheridan is an MSP for the Solidarity party
The Solidarity MSP's staff called in officers on Thursday after a "device" was found in his car while he was travelling back to Holyrood.
Lothian and Borders Police have taken the item away for examination.
Mr Sheridan said the device had a "wee aerial" on it and that he was "concerned and very angry". He is due to meet officers on Friday.
His car was being kept overnight by the police, who asked him not to release any further details.
Last year the former Scottish Socialist Party leader won £200,000 in damages from the News of the World over stories which alleged he was a "swinger" and had cheated on his wife Gail.
Following the verdict prosecutors ordered police to carry out a criminal investigation into allegations of perjury during the defamation case.
The News of the World is seeking to overturn the court's verdict and an appeal is due to be heard in December.
The tabloid later produced a video it claimed showed Mr Sheridan admitting he had visited a swingers' club.
The footage was dismissed as a "concoction" by the MSP, who claimed to be the victim of "sinister forces".
After the tape emerged, Mr Sheridan told a press conference that he believed the British state was orchestrating a plot against him.
He said: "The state has a fine history of trying to destabilise and undermine socialist movements or trade union struggles.
"And when the history of this whole episode is written about, I think you'll find that MI5 certainly was involved."
The trial split the Scottish Socialist Party, with senior members and MSPs giving evidence for both sides.
The acrimony within the party culminated in Mr Sheridan and another MSP, Rosemary Byrne, leaving to set up the breakaway left-wing party Solidarity.
Colin Fox, who replaced Mr Sheridan as SSP convener, said he was "flabbergasted" by the latest development.
The MSP said: "It's another bizarre twist in the tale.
"I'm as surprised as anybody by this. I don't know who would want to bug Tommy Sheridan.
"I await with interest to find out what this item is that Lothian and Borders Police have picked up."