News International said in a statement that it was "prevented by confidentiality obligations" from discussing some of The Guardian's allegations, but said it worked to ensure its journalists operated within the law.

Murdoch refused to comment.

"I'm not talking about that issue at all today. Sorry," he told FOX Business Network at a media conference in Sun Valley, Idaho.

The Guardian said in a statement that the police should share their evidence with the lawmakers on the House of Commons Culture and Media Committee that reviews media practices.

Most of the claims in The Guardian story date from 2006. The newspaper said Paltrow was targeted by private investigators after she had given birth to her son, Moses, and George Michael the same year he had been photographed dozing behind the wheel of his car.

Spokespeople for Paltrow and Michael did not immediately return calls seeking comment.

Goodman was jailed for four months in 2007 for hacking into royal officials' voice mail systems. His accomplice, private investigator Glenn Mulcaire, was sentenced to six months in prison for hacking into the messages, including some from Princes William and Harry. The judge said Mulcaire duped mobile phone network operators into passing him confidential PIN numbers to access messages left on the cell phones.

News International executives said Goodman acted without the knowledge of other journalists or editors.

Yates said police had found that Goodman and Mulcaire had a list of hundreds of "potential targets," but that only a small number of phones had actually been hacked

"In the vast majority of cases, there was insufficient evidence to show that tapping had actually been achieved," he said.

The Guardian's report reignites a long-simmering debate about the ethics of Britain's newspapers, which compete aggressively for readers and stories, and routinely deploy cash handouts and subterfuge to get scoops. An exclusive about a politician or celebrity can mean hundreds of thousands of extra copies sold for a tabloid such as News of the World, which has a circulation of about 3 million.

Prime Minister Gordon Brown said The Guardian's allegations raised "questions that are serious and will obviously have to be answered."

Britain's Data Protection Act makes it an offense to "obtain, disclose or procure the disclosure" of personal information without consent.

But in 2006, Information Commissioner Richard Thomas, Britain's data-protection watchdog, said in a report that there was "an unlawful trade in confidential personal information," with much of it going to the media.