DAVID Cameron's former communications chief, Andy Coulson, has been detained on suspicion of committing perjury during the trial of former MSP Tommy Sheridan.
The 44-year-old was detained in London this morning by officers from Strathclyde Police.
Mr Coulson gave evidence in December 2010 at Sheridan's perjury trial at the High Court in Glasgow.
It is understood he is now on his way to the city.
Sheridan was ultimately 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.
Operation Rubicon detectives have been looking at whether certain witnesses lied to the court during Sheridan's trial as part of a "full" investigation into phone hacking in Scotland.
A Strathclyde Police spokesman said: "Officers from Strathclyde Police Operation Rubicon detained a 44-year-old man in London this morning under Section 14 of the Criminal Procedures Scotland Act on suspicion of committing perjury before the High Court in Glasgow.
"It would be inappropriate to comment any further at this time."