Gordon Brown has launched an all-out attack on News International accusing it of using "disgusting" methods to gain access to personal information.
The former prime minister also alleged the newspaper giant had links to the "criminal underworld".
And he accused The Sunday Times of gaining access to his personal bank and legal files when he was chancellor.
News International said it would investigate Mr Brown' s allegations and wanted to see all the information.
Mr Brown remained silent about alleged abuses of media power during his time in office - but he has been prompted to speak out by fresh claims in The Guardian that he had been targeted by News International newspapers.
'Incredibly upset'
In an interview with BBC News, the Labour MP said he was "in tears" when he was told by News International journalists that the Sun had details of his son Fraser's medical condition - he has cystic fibrosis - as he had wanted the information to be kept private.
"Sarah and I were incredibly upset about it, we were thinking about his long term future, we were thinking about our family," he said.
He said he did not know how the newspaper had got access to the details: "The fact is, it did appear and it did appear in the Sun newspaper."
News International said the Sun newspaper is satisfied about the methods in which it obtained the story about Mr Brown's son's medical condition.
In separate allegations, it is claimed personal details were obtained for a front-page Sunday Times report that Mr Brown had bought a flat owned by Robert Maxwell at a "knock-down price".
Mr Brown told the BBC the story had been "completely wrong" but the company had been "trying to prove a point" and had aimed to bring him down as chancellor.
He also alleged the newspaper had got access to his building society account and legal files: "I'm shocked, I'm genuinely shocked to find this happened because of the links with known criminals who were undertaking this activity, hired by investigators who were working with the Sunday Times."
He added: "If I, with all the protection and all the defences and all the security that a chancellor of the exchequer or a prime minister has, is so vulnerable to unscrupulous tactics, unlawful tactics, to methods that have been used in the way that we've found - what about the ordinary citizen?
"What about the person - like the family of Milly Dowler - who were in the most desperate of circumstances, at the most difficult occasions in their lives - in huge grief ... and then they find that they are totally defenceless in this moment of greatest grief from people who are employing these ruthless tactics?"
Medical condition
He said he had complained to the Sunday Times at the time, through his lawyers - but had not complained to the police because he had only recently "found out about the links between the Sunday Times and what I would call elements of the criminal underworld ... to do work which, if you like, is the most disgusting of work - not against me only but against people who were completely defenceless".
The Guardian newspaper has reported that a conman working for the Sunday Times was used to get access to Mr Brown's files from his London lawyers - the conman was later jailed for fraud in relation to a different matter.
Mr Brown dismissed claims that he had done little to tackle alleged abuses of press power when he was in office, claiming that in his final months in office, he had wanted a judicial inquiry.
But he added: "At the time however there was very few people who accepted this was the right thing to do."
He also claimed that he had "stood up" to News International's commercial ambitions when he thought they were against the public interest - and he urged an inquiry into the alleged abuse of power by the media.
Former Labour home secretary Alan Johnson told the BBC he did not call for an investigation into the original hacking inquiry because it would have been seen as a "low political blow" against Andy Coulson - an ally of then opposition leader David Cameron.
A spokesman for News International said: "We note the allegations made concerning the reporting of matters relating to Gordon Brown. So that we can investigate these matters further, we ask that all information concerning these allegations is provided to us."
It comes after a week of allegations about phone hacking at another News International title, the News of the World, which is accused of using a private investigator to listen to the mobile phone messages of murdered schoolgirl Milly Dowler.
News International, which is carrying out an internal investigation into allegations of wrongdoing at its newspapers, said it wanted to see all of the information.
