Gordon Brown, the former prime minister of Britain, is the first in a string of current and former political leaders to appear in front of the Leveson Inquiry into media ethics in London.
In the testimony he delivered on Monday, Brown criticised newspapers owned by media tycoon Rupert Murdoch for sensationalising coverage of serious issues like the United Kingdom's involvement in Afghanistan.
The judge-led inquiry was set up last year, after a scandal revealed that British tabloid News of the World had hacked the mobile phone voice mails of scores of celebrities, politicians and even crime victims in its quest for scoops.
He said the newspaper had made a series of spurious claims, for example, that he had fallen asleep during a service of remembrance for dead troops. Brown said he had been bowing his head in prayer.
"The whole weight of their coverage wasn't what we had done and whether we had done the right thing, but was that I personally did not care about our troops in Afghanistan, and that is where you conflate fact and opinion," he said.
Brown also deplored the Sun's publication of a story revealing that his four-month old son had cystic fibrosis, a story neither he nor his wife had given consent for.
"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 leaking it which we never did of course - was obtained in another way," he said.
This claim contradicts the testimony of Rebekah Brooks, the then editor of the Sun, who told the inquiry in May that Brown had not objected to the story being published.
According to Brown, the Sun has lied about how they sourced the story.
"I don't think there's any parent in the land who would have made the choice that we are told we made to give explicit permission for that to happen. So there was no question ever of explicit permission," he said.
Brown said he and his wife Sarah had been distressed by the leak, but acknowledged that Sarah had remained friendly with Brooks, and even organised a 40th birthday party for her in 2008.
Brooks, along with her husband and four aides, was charged last month with conspiring to pervert the course of justice in connection with the phone hacking scandal.
During his 2007-2010 term in office, Brown had a testy relationship with Murdoch and his press.
The Sun backed the Conservative party over Brown's Labour party in the 2010 national election. The election ejected Brown from power and produced a Conservative-Liberal Democrat coalition government.
Brown denied that he had declared war on News Corp in a phone call with Murdoch in 2009, after the Sun switched its backing to the Conservatives.
"This conversation never took place. I'm shocked and surprised that it should be suggested even when there is no evidence of such a conversation that it should have happened," he added.
Later on Monday, Finance Minister George Osborne will appear in front of the London Inquiry, while Prime Minister David Cameron is due on Thursday.