The former Deputy Prime Minister John Prescott attacked David Cameron today for failing to take action against his director of communications amid the phone tap allegations.
Mr Cameron was said by a Tory party spokeswoman to be "very relaxed about the story" involving Tory director of communications Andy Coulson - the former editor of the News of the World.
Mr Prescott, who says he wants answers from police over claims they knew his phone was tapped by private investigators working for journalists, said he was "staggered" the Tory leader was "relaxed" about the role played by Mr Coulson.
Mr Prescott accused Mr Cameron of double standards after the Tory leader had demanded the Government sack Damian McBride, the Downing Street aide who resigned amid the Tory email-slur saga.
The former deputy Prime Minister told BBC Breakfast: "If these allegations are to be believed, the enormity of it is unbelievable.
"I am actually staggered that Mr Cameron, who employed Mr Coulson, who was the editor at the time through all these allegations, says he's quite relaxed about these allegations.
"I find that staggering particularly when he demanded that Mr McBride (was sacked). To say he's relaxed about this is just unbelievable."
MPs from all three parties, including Mr Prescott and Cabinet minister Tessa Jowell, were among the targets of alleged phone taps by journalists working for News Group Newspapers, The Guardian said.
Mr Coulson said last night he had "no knowledge whatsoever" of any settlement with Gordon Taylor, chief executive of the Professional Footballers Association.
But Mr Prescott added: "He (Mr Coulson) should come before the committee and explain what he did know. It's time for him to speak out and it's time for Mr Cameron to ask the essential questions that he can certainly find out if he reads the Guardian."
Mr Coulson resigned from the News of the World after royal editor Clive Goodman was sentenced to four months in prison in January 2007 for plotting to hack into telephone messages belonging to royal aides.
PR agent Max Clifford is another whose phone was allegedly hacked into, according to the Guardian.
He said the claims raised "lots of serious questions".
Mr Clifford - who works with some of Britain's best known celebrities - told the BBC: "If these allegations prove to be true, then it's something that an awful lot of people are going to very unhappy about."
He also asked: "Why has this just come out? According to the Guardian, it's come from police sources If the police had this information, why didn't they act on it?
"There are lots of questions that need to be answered, serious questions."