Prime Minister David Cameron came under renewed pressure to detail his relations with scandal-hit News Corp on Thursday and the spotlight fell on other newspaper groups when an official said police were reviewing their reporting methods.
Facing the worst crisis of his premiership, Cameron appeared to have shored up his authority among Conservative supporters and his Liberal Democrat coalition partners with a confident performance in an emergency parliamentary debate on Wednesday.
But answers which critics described as evasive over his discussions with News Corp officials over their takeover bid for broadcaster BSkyB were seized on by Labour to portray the prime minister as tainted by the scandal.
The inquiry is centered on the News of the World, closed down this month by Murdoch after 168 years, but risks dragging in other newspapers in a declining and ultra-competitive market.
Police are reviewing a report compiled by Britain's Information Commissioner in 2003 which detailed the use by a string of newspaper groups of a firm of private investigators to obtain details about story targets, the commissioner said.
It's a rich source of possibly corroborative evidence in some cases, Christopher Graham told BBC Radio on Thursday.
Police have already said their investigation is not confined to Rupert Murdoch's News of the World, but this was the first confirmation that the 2003 Information Commission report, largely ignored at the time, was now being reviewed.
Sly Bailey, chief executive of Britain's Trinity Mirror Plc, has written to the head of parliament's media committee to complain after a lawmaker suggested one of its national papers had been involved in hacking.
Cameron told parliament he regretted the uproar caused by hiring a former newspaper editor at the heart of a crisis that has engulfed News Corp and raised questions about his judgment.
But he refused an outright apology for taking on former News of the World editor Andy Coulson. And his critics also seized on his failure to deny in parliament that News Corp executives raised their plans to take full control of pay-TV network BSkyB during informal meetings with him.
On at least nine occasions, David Cameron failed to give a direct and full response to legitimate questions about whether he discussed BSkyB with News Corp and News International executives, said Labour media affairs spokesman Ivan Lewis.
Cameron told parliament he had no inappropriate discussions on BSkyB and was not involved in a government decision to give official blessing to the takeover. News Corp dropped the bid last week due to the phone-hacking scandal.
Lewis said: David Cameron needs to come clean and provide complete transparency. Until he does so there will continue to be serious questions about his judgment.
Labour, ousted from power last May after 13 years during which they too courted Murdoch's favor, appear prepared to play a long game, exploiting the scandal to hamper Cameron.
Leader Ed Miliband has not called for him to quit but his party seems set on using the likely drip-feed of developments in the affair to gradually erode his authority at a time when government spending cuts risk adding to its unpopularity.
POLICE STEP UP INVESTIGATION
News Corp dropped its $12 billion bid for the 61 percent of BskyB it does not own and shut down the scandal-hit News of the World tabloid this month after a wave of public revulsion following allegations that the newspaper hacked into the voicemails of a murdered teenage schoolgirl.
Those claims turned a long-running saga into what Cameron himself called a firestorm, which has prompted the resignations of senior News Corp executives Rebekah Brooks and Les Hinton and also forced two senior police chiefs to quit.
The scandal has rippled around the globe, with politicians in Murdoch's native Australia saying they were considering strengthening their privacy laws.
London police, criticized for the way they initially handled the case, have boosted their team to 60 officers from 45 investigating allegations that the newspaper listened in to the voicemails of as many as 4,000 people to try to get scoops.
Pursing the allegations with renewed vigor, London police have arrested and bailed 10 people since the start of the year including former News of the World editors Brooks and Coulson.
A source has told Reuters that detectives have cryptic financial records corroborating suspicions that Coulson, who served as a spokesman for Cameron from mid-2007 until January this year, had known when editor of the News of the World until early 2007 about illegal payments to police.
The cash records tally with payments suggested in an e-mail discussion between Coulson and the newspaper's disgraced royal correspondent, Clive Goodman, who was jailed along with a private investigator in 2007 for hacking the phones of royal aides. That conviction prompted Coulson to resign, although he has since maintained he had known of no wrongdoing at the paper.
The existence of the e-mails has already been reported in British media. According to Reuters' source, who has been briefed on internal News International discussions, the message traffic shows Coulson and Goodman corresponded about paying a police contact for restricted information, including phone numbers, of members of the British royal family.
Glenn Mulcaire the private investigator jailed along with Goodman in 2007 has no plans to speak out about the case until the police investigation is complete, his lawyer said on Thursday.
News International said this week they has stopped paying his legal fees, prompting speculation that Mulcaire might reveal more details of who he worked with at News of the World.
(Editing by Philippa Fletcher)