Today, former Prime Minister Brown told the Leveson under oath that he never made an 'unbalanced' call to the media mogul after The Sun shifted its support to the Conservatives ahead of the 2010 election.
However, almost immediately after Brown had completed his evidence, Murdoch's News Corp issued a statement in response, saying: "Rupert Murdoch stands behind his testimony."
Appearing at the Leveson Inquiry in April, the 81-year-old billionaire detailed the implosion of his relationship with Brown.
Murdoch claimed that Brown phoned him at the time The Sun shifted its allegiance, and said: "Well, your company has declared war on my government and we have no alternative but to make war on your company."
Asked why the former Labour leader would say that, Murdoch replied: "I don't think that he was in a balanced state of mind."
However, Brown took the stand at the Leveson today and denied that the call had ever taken place.
"This call did not happen, this threat was not made," he said.
"I couldn't be unbalanced on a call that I didn't have... and I find it shocking that we should get to this situation some time later when there is no evidence of this call happening at the time that he says it happened and you to be told under oath that this was the case."
Later, Brown added: "I would rather have been an honest one-term prime minister than a dishonest two-term prime minister."
Also during the session this morning, Brown again denied The Sun's claims that it had a legitimate source for a story about his son Fraser's medical condition in 2006.
He pointed out that NHS Fife has admitted that it is "highly likely" a member of its staff spoke about the diagnosis of cystic fibrosis of the then-Chancellor of the Exchequer's son to reporters.
Current chancellor George Osborne is currently giving evidence to the Leveson Inquiry about News Corp's Sky bid and his relationship with the Murdochs.
Also this week, ex-Conservative Prime Minister Sir John Major, current Tory Prime Minister David Cameron and his deputy leader Nick Clegg will all give evidence.