The tabloid is owned by News International Ltd., a subsidiary of Rupert Murdoch's News Corp. The company said in a statement that it would be "inappropriate to comment at this time."

Former Deputy Prime Minister John Prescott, one of the alleged targets, said he had suspected his phone was tapped. He said he wanted to know why he had not been told by police.

He said that "for such a criminal act not to be reported to me, and for action not to be taken against the people who have done it, reflects very badly on the police, and I want to know their answer."

Former Home Secretary Charles Clarke said that the allegations in The Guardian raised serious questions for News International, the Conservatives, and the police.

"I think it is outrageous," he said. "I think we do need action immediately."