Former editors of the News of the World newspaper, including British Prime Minister David Cameron's former media chief Andy Coulson, were aware that phone-hacking was taking place at the tabloid, one of its ex-reporters told a public inquiry on Tuesday.

Paul McMullan said the practice had not been uncommon among the rank and file reporters at the paper, part of Rupert Murdoch's News Corp which he shut down in July amid public fury at revelations of phone-hacking by the paper.

The furore prompted Cameron to order a public inquiry into press standards which began its hearings this month.

Asked if editors at the paper knew voicemails on mobile phones were being intercepted, McMullan told the inquiry: We did all these things for our editors, for Rebekah Brooks and for Andy Coulson.

Coulson quit as editor of the paper in 2007 when its royal correspondent was jailed for phone-hacking. He denied any knowledge of the practice, which News International, News Corp's British arm, said had been the work of a rogue reporter.

Cameron took him on as his communications chief shortly afterwards, a decision critics say casts serious doubt on his judgement. Coulson resigned from the post in January.

My assertion has always been Andy Coulson brought that practice wholesale with him when he was appointed deputy editor, McMullan said, referring to phone-hacking.

McMullan defended hacking, saying it was a perfectly acceptable tool in trying to get to the truth but called Brooks and Coulson the scum of journalism for trying to shift the blame onto him and other colleagues.

Brooks quit as chief executive of News International in July and both she and Coulson have been arrested and bailed by police investigating the hacking allegations.

(Reporting by Michael Holden; Editing by Mark Heinrich)