London (CNN) -- Former British Prime Minister Gordon Brown lashed out Monday at press baron Rupert Murdoch, his son and his British newspapers, raising the stakes in a highly charged and very public battle between the two men.
The conflict could affect whether Murdoch keeps control of the British part of his media empire.
During his testimony before the Leveson Inquiry, the former British leader flatly denied the most sensational claim that Murdoch made when he testified at the media ethics inquiry this year: that Brown had "declared war" on Murdoch's company when a top-selling Murdoch newspaper endorsed the Conservative party rather than Brown's Labour party in 2009.
"This conversation never took place. I am shocked and surprised" that Murdoch said it had when he was grilled at the inquiry in April, Brown said Monday. "There was no such conversation."
Brown repeatedly insisted that there was "no evidence" of the phone call, basing his assertion on phone records from his office when he was prime minister.
The media tycoon said in April that Brown had phoned him and threatened him when the Sun newspaper pulled its support for Labour and switched to the Conservatives.
"He said, 'Well, your company has made -- declared war on my government, and we have no alternative but to declare war on your company.' And I said, 'I'm sorry about that Gordon, thank you for calling.' End of subject," the News Corp. chairman testified.
After Brown essentially accused Murdoch of lying under oath, News Corp. said its chairman stood by his testimony.
Murdoch's British operations are under scrutiny after revelations of widespread phone hacking by people working for his newspapers. Police and lawmakers are conducting separate inquiries into the scandal, separately from the Leveson Inquiry.
On Monday, London's Metropolitan Police recommended that prosecutors press charges against five journalists as part of Operation Weeting, the police investigation into phone hacking.
Additionally, if British media regulators feel Murdoch is not a "fit and proper person" to hold a British broadcasting license, he could theoretically be stripped of control of British Sky Broadcasting, a lucrative part of his worldwide operations.
Brown also attacked Murdoch's Sun newspaper for its reporting of sensitive medical information about his infant son Fraser.
And he accused Murdoch's son and heir apparent James of "breathtaking arrogance" and a desire to gut British rules on the impartiality of the media.
Brown insisted he had never given permission for the Sun newspaper to report that Fraser had cystic fibrosis, and he rejected the Sun newspaper's explanation that it had heard about the condition from a person who also had a sick child in the hospital.
The judge-led Leveson Inquiry, set up by British Prime Minister David Cameron after the phone hacking scandal at Murdoch's News of the World newspaper last summer, is a wide-ranging investigation examining the relationship between the media and politicians.
Cameron, who has been under pressure because of his ties to Murdoch and his former newspaper chief Rebekah Brooks, is scheduled to testify all day Thursday at the Leveson Inquiry.
Chancellor of the Exchequer George Osborne will also be quizzed Monday.
John Major, another former prime minister, will appear Tuesday, as will opposition Labour Party leader Ed Miliband and his deputy, Harriet Harman.
Deputy Prime Minister Nick Clegg is scheduled to testify Wednesday, ahead of Scottish First Minister Alex Salmond.
Former Prime Minister Tony Blair has already testified. In his testimony, said he came under "political pressure" from Murdoch during his time in office but denied that his relationship with the media baron was too "cozy."
In April, Cameron told politicians in the House of Commons: "I think we all, on both sides of this house, did a bit too much cozying up to Mr. Murdoch."
Cameron's judgment in hiring former News of the World editor Andy Coulson as his communications director has also been called into question.
Coulson resigned from the Downing Street role early last year when police began a new phone hacking investigation, saying it had become a distraction. He quit the News of the World after two employees were jailed over phone hacking in 2007 but denies knowing of wrongdoing while he was in charge.
Coulson was this month arrested and charged with perjury over court testimony about phone hacking, according to Britain's Press Association news agency.
Cameron established the Leveson Inquiry after British public anger at the News of the World about the hacking of voice mail messages of a missing teenage girl who turned out to have been murdered.
The case of Milly Dowler came on top of apologies from the tabloid for the hacking of the phones of celebrities and politicians, and proved to be the last straw for the paper, which was shut down in July.
The inquiry is intended to explore press ethics in Britain more widely, alongside police investigations into phone hacking, e-mail hacking and police bribery by people working for Murdoch's British newspapers.
CNN's Laura Smith-Spark and Bharati Naik contributed to this report.