James Murdoch's behind-the-scenes lobbying campaign spilled out into the public domain Tuesday as documents detailing his close ties to the British establishment were examined by a judge-led inquiry into media ethics.

The nature of the Murdoch family's links with senior politicians is one of the key questions raised by Britain's phone hacking scandal, which has rocked the British establishment with revelations of media misdeeds, police corruption and corporate malpractice.

Critics of Rupert Murdoch's News Corp., the global media empire owned by James' father, claim the company's close ties to top U.K. leaders helped boost its business agenda and allowed it to get away with illegal activities for years.

Some allege that Murdoch's influential newspapers helped squeeze favours from loyal politicians. In particular, they argue that Rupert Murdoch's multibillion-dollar bid for the lucrative British Sky Broadcasting Group PLC was rubber-stamped by Britain's Conservative Party leaders in return for favourable press coverage.

James Murdoch, showing little emotion, repeatedly denied the charge Tuesday.

"I would never have made that kind of a crass calculation. It just wouldn't occur to me," he testified under oath at Lord Justice Brian Leveson's inquiry into media ethics.

Murdoch's comments gave a feel for his company's considerable sway, detailing 20-odd dinners, lunches, breakfasts and other meetings with Prime Ministers David Cameron, Gordon Brown and Tony Blair between 2004 and 2010.

Murdoch was also in close contact with British treasury chief George Osborne — visiting him at his retreat in Buckinghamshire — and Conservative government minister Jeremy Hunt, who once went so far as to describe himself as "a cheerleader for Rupert Murdoch's contribution to British television."

Murdoch quizzed over BSkyB bid

Over four hours of testimony, Murdoch was quizzed about his wide-ranging access to confidential government discussions about his bid for BSkyB in 2011. At the time, News Corp. was lobbying to be allowed to increase its share in BSkyB from around 40 per cent to 100 per cent, a potentially lucrative but sensitive move opposed by many competitors in the media industry.

After the phone hacking scandal broke last July, News Corp. abandoned that bid to take over BSkyB.

Hunt — who's now the minister charged with overseeing the 2012 London Olympic Games — repeatedly gave Murdoch intelligence on his political opponents and provided the inside track on what the government was doing, according to emails made public at the inquiry.

"Do you think it's appropriate, Mr. Murdoch, that here you are getting confidential information as to what's going on at a high level of government?" asked inquiry lawyer Robert Jay.

Murdoch hesitated before giving an awkward laugh.

"What I was concerned with here was the substance of what was being communicated, not the channel by which it was communicated," he said.

Murdoch defends his record

Earlier in the hearing, James Murdoch defended his record at the head of his father's scandal-plagued British newspaper arm, saying that subordinates prevented him from making a clean sweep at the now-defunct News of the World tabloid. He repeated allegations that the tabloid's then-editor Colin Myler and the company's former lawyer Tom Crone misled him about the scale of illegal behaviour at the newspaper.

Leveson asked Murdoch: "Can you think of a reason why Mr. Myler or Mr. Crone should keep this information from you? Was your relationship with them such that they may think: 'Well we needn't bother him with that' or 'We better keep it from it because he'll ask to cut out the cancer'?"

"That must be it," Murdoch said. "I would say: 'Cut out the cancer,' and there was some desire to not do that."

Revelations that reporters at the News of the World had hacked into the phones of hundreds of high-profile people, including a teenage murder victim, prompted Rupert Murdoch to close the 168-year-old newspaper last summer.

The scandal has triggered three U.K. police investigations, led to more than 100 lawsuits and launched Leveson's inquiry into media practices.