UPDATE 1-Cameron's ex-media chief accused of hypocrisy over affair
(Adds later evidence)
LONDON, April 24 (Reuters) - Prime Minister David Cameron's ex-media chief was accused on Thursday of pure hypocrisy when, as editor of a Rupert Murdoch tabloid, he exposed a government minister's affair while conducting his own extra-marital relationship.
Appearing in the witness box for the sixth day at the tabloid phone-hacking trial at the Old Bailey, Andy Coulson said he regretted revealing in 2004 that then interior minister David Blunkett was having an affair.
Coulson also admitted he had not disclosed any knowledge of phone-hacking by a reporter involved in the story because he was concerned about its impact.
Coulson, who denies conspiracy to hack into mobile phone voicemails, had told the jury last week that reporter Neville Thurlbeck on the now defunct News of the World had once played him excerpts of voicemail messages left by Blunkett on the mobile phone of a woman with whom he was having a relationship.
That enabled Coulson to confront Blunkett about the relationship and splash the story on the paper's front page.
Coulson has also told the trial he was engaged in an on-off relationship with his co-defendant Rebekah Brooks, another former Murdoch editor who went on to run the British newspaper arm of News Corp.
"This story was about someone's private life and, given what is going on in my own private life, the irony is not lost on me," the 46-year-old told the court.
"Pure hypocrisy isn't it?" he was asked by David Spens, the lawyer for another co-defendant, Clive Goodman.
After a pause Coulson replied: "The irony is not lost on me."
Coulson left the mass-selling Sunday tabloid in 2007 when Clive Goodman, his royal editor, admitted hacking into the phones of royal aides. Coulson said he had not known about the practice but had left to take full responsibility for the crime.
Facing questions from Spens, Coulson said he had not asked Thurlbeck who showed him the hacked messages from Blunkett where they had come from, saying that he had just told the reporter to stop.
"You are a very bright, intelligent man with a questioning mind," Spens said to him about his failure to ask questions.
Coulson replied: "I'm not telling the jury I wasn't curious, I'm telling the jury what happened. The most important thing in my mind was I stopped it."
The court heard that Coulson said he had decided not to volunteer any information to detectives investigating Goodman and phone-hacking in 2006, including knowing that Thurlbeck had recordings of hacked voicemails.
"The reason was that would have come back to you and your knowledge of phone-hacking, wouldn't it?" Spens put to him.
"Yes, I accept that," Coulson replied.
Spens said he had been "concerned to save your own skin".
"I would certainly accept that the impact on me was a factor but there were other factors as well, the paper, the company, they were all part of that decision," Coulson said.
Thurlbeck is one of four former News of the World journalists who admitted phone-hacking offences before the start of the trial.
Coulson and Goodman both deny charges of making illegal payments to police officers. Brooks has also pleaded not guilty to charges over phone-hacking and other offences.