Ex-Prime Minister Gordon Brown says lessons cannot be learned about press standards unless there is honesty about how details of his son’s cystic fibrosis were published by the Sun.
He said he and his wife Sarah were “presented with a fait accompli” by the paper, before it ran a story on their son Fraser’s medical condition in 2006.
He denied that he or his wife had given permission for the story to be run.
Mr Brown is giving evidence to the Leveson Inquiry into press standards.
In a key week for the inquiry, Chancellor George Osborne will be giving evidence later and Prime Minister David Cameron will enter the witness box on Thursday.
The inquiry, which is currently focusing on the relationship between the press and politicians, is resuming after a week-long adjournment.
The paper’s then-editor Rebekah Brooks had previously told the Leveson Inquiry she had the express permission of the Browns to run the story about Fraser’s medical condition, but the Browns have previously said that was “untrue”.
Mr Brown told the inquiry he had been given an apology by the NHS in Fife because they think it “highly likely” unauthorised information was disclosed by NHS staff about Fraser Brown.
He again denied that consent had been given to the Sun to publish the story.
“I find it sad that even now, in 2012, members of the News International staff are coming to this inquiry and maintaining this fiction that a story that could only have been achieved or obtained through medical information or through me or my wife… was obtained in another way.
“We can’t learn the lesson about what has happened with the media anything unless there is some honesty about what actually happened, whether payment was made and whether this is a practice which could continue.”
Shortly after he spoke about NHS Fife to the Leveson Inquiry, John Wilson, its chief executive said: “We now accept that it is highly likely that, sometime in 2006, a member of staff in NHS Fife spoke, without authorisation, about the medical condition of Mr Brown’s son, Fraser.
“With the passage of time it has not been possible to identify all the circumstances.
“We believe, however, that there was no inappropriate access to the child’s medical records. We are quite clear that conversations about patients are just as much a breach of confidentiality as looking into their medical records.”
Mr Brown also criticised other examples of Sun journalism during his time in office, including a claim he fell asleep at a memorial service when, he explained, he had actually bowed his head to pray.
He explained: “There’s a story you fell asleep but you were praying and the Sun decides this is an example of someone falling asleep and dishonouring the troops,” he said.
Mr Brown mentioned how the Sun had portrayed him on a number of occasions in relation to Afghanistan.
Mr Brown began his testimony by saying he had had a “period of enforced reflection, courtesy of the British people” to think about the relationship between Westminster and Fleet Street.
He went on to say that media in Britain, at its best, is the “best in the world” but said that one of the key problems of the press is the conflation of fact and opinion – mirroring the views stated by his predecessor Tony Blair when he appeared at the Leveson Inquiry two weeks ago.
The former prime minister is likely to be questioned about his relationship with Rupert Murdoch during his time in government with Labour.
The News Corp boss told the inquiry in April that Mr Brown had phoned him in an “unbalanced” state of mind and declared war on his media empire after the Sun newspaper had switched its support from Labour to the Conservatives in 2009.
The former PM later denied having made such a threat.
The chancellor, meanwhile, will be asked about the hiring of Mr Coulson in 2007 after he quit the News of the World in the wake of the conviction of the paper’s royal editor for phone hacking.
Mr Osborne will also be asked about his communications with Culture Secretary Jeremy Hunt on the day Mr Hunt was handed responsibility for the BSkyB bid.
Labour leader Ed Miliband, former Conservative Prime Minister Sir John Major and Deputy Labour Leader Harriet Harman will give evidence to the inquiry at London’s Royal Courts of Justice on Tuesday.
Deputy Prime Minister Nick Clegg and Scotland’s First Minister Alex Salmond will appear on Wednesday, while Mr Cameron will be the sole witness on Thursday.