Police chiefs are studying allegations of large-scale phone-hacking by the News of the World.
The Metropolitan Police is urgently trying to "establish the facts" after claims its officers failed to act on evidence that reporters targeted politicians and celebrities with illegal methods.
The row has also piled pressure on Conservative PR chief, Andy Coulson, who was the editor of the Sunday tabloid newspaper at the time of the alleged practices.
Conservative leader David Cameron moved to defend his director of communications as Labour MPs lined up to demand his sacking, comparing him to ousted Labour spin doctor Damian McBride.
The cross-party Culture, Media and Sport Select Committee announced that it was reopening an inquiry it held after the News of the World's royal editor, Clive Goodman, was jailed for using illegal surveillance techniques.
The committee's chairman, Tory MP John Whittingdale, said it would be asking former News International chief Les Hinton whether he wished to amend his previous assertion that no other journalists knew of Mr Goodman's activities.
He said the committee may also call Mr Coulson to give evidence, among several present and former News International executives.
Those allegedly targeted by the News of the World included former deputy prime minister John Prescott, Mayor of London Boris Johnson and celebrities including actress Gwyneth Paltrow and celebrity chef Nigella Lawson.
Mr Prescott, who has led calls for Mr Coulson to be fired, has also criticised the Met for failing to inform him that journalists were trying to access his phone messages.
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