Former News of the World Editor Andy Coulson is currently being held at Govan Police Station in Glasgow.
Coulson who also worked as David Cameron's Director of Communications is being questioned by Strathclyde Police as part of a perjury investigation following the trial of Tommy Sheridan.
The 44-year-old was detained by officers from Strathclyde Police who travelled to London on Wednesday. Coulson was then driven to Govan Police Station in Glasgow, where he remains tonight. In Scottish law 'detained' means he will be questioned and then could later be released or arrested.
Coulson's detention comes as part of Operation Rubicon. As part of the operation detectives have been looking at whether certain witnesses lied to the court during Tommy Sheridan's trial as part of a "full" investigation into phone hacking in Scotland.
Mr Coulson, then employed by Downing Street as director of communications, told the trial in December 2010 he had no knowledge of illegal activities by reporters while he was editor of the News of the World.
He also claimed: "I don't accept there was a culture of phone hacking at the News of the World."
Tommy Sheridan was jailed for three years in January 2011 after being found guilty of perjury during his 2006 defamation action against the News of the World.
He had been awarded £200,000 in damages after winning the civil case but a jury at the High Court in Glasgow found him guilty of lying about the now-defunct tabloid's claims that he was an adulterer who visited a swingers' club.
Sheridan's trial, which lasted almost 12 weeks, was one of the longest of its kind in Scottish legal history.
He was convicted of five out of six allegations in a single charge of perjury relating to his evidence during the civil action at the Court of Session in Edinburgh.
His wife Gail was on trial along with him but was acquitted of lying to the court during his successful defamation action against the News of the World in 2006.
He was released from jail in January after serving one year of his sentence and vowed to continue the fight to clear his name.