Former Conservative MP Louise Mensch, who was a member of the parliamentary committee investigating phone hacking, said journalists told her that the practice was "widespread" within the industry.
Ms Mensch said: "I remember during the parliamentary inquiry into hacking, I was very clear, journalists were coming to me all the time saying this was a widespread practice in Fleet Street, and the further we get into it the more true that becomes."
Earlier, it was revealed that former Daily Mirror editor Piers Morgan was questioned under caution last December about phone hacking but was not arrested.
The publication of topless photographs of a shadow cabinet minister would be a "humiliation" for any newspaper or magazine involved and not for the Labour politician, a former MP has said.
Gloria de Piero has called on the media to "call off the hunt" for the photos, taken when she was 15 or 16, after being told that thousands of pounds were being offered for them.
Former Conservative MP Louise Mensch said the pictures should not be printed, but added that if they were it would only draw attention to the Ashfield MP's "courageous and dignified" reaction to the threat of exposure.
Ms Mensch responded to the threat of stories about drunkenness and drug-taking in her youth by going public with an admission.
The former Corby MP told BBC Radio 4's Today programme:
"I don't think it matters whether they print the pictures or not. If they do it will only be to her credit. Her dignified response and refusal to renounce her past only speaks well of her character and her guts and that's the kind of people we want in politics.
"Women in particular, I think, will be cheered by her refusal to be cowed by this quasi-sexual or moralistic assault on her behaviour as a 15-year-old girl."Publish and be damned. It would be a humiliation to whoever publishes them and not to her."
Former Conservative MP Louise Mensch told ITV's This Morning that Margaret Thatcher "gave you this overwhelming sense that women could do anything".
The former Conservative MP Louise Mensch, who quit her Corby seat to move to America, has commented on her party losing her seat in the by-election:
The former Conservative MP Louise Mensch has effectively declared Labour winners of the by-election in her former constituency in a series of tweets posted just after the polls closed:
The result will not be known until tomorrow afternoon as counting will start in the morning.
Louise Mensch, who recently resigned as Conservative MP for Corby, says Nadine Dorries is "demeaning the role of an MP" by choosing to appear on the reality TV show I'm A Celebrity.
Writing in The Guardian, Ms Mensch highlights her decision to bow out of Parliament "because I could not make family life work with my husband on another continent".
She writes that Ms Dorries "made her choice, preferring the cameras to weeks of parliamentary votes, skipping out on the autumn statement - a crucial piece of government business - in the process".
"As a seasoned media performer, Dorries knows how to work a message. She must have had some idea how unpopular this move would be", Ms Mensch wrote.
She adds the Mid Bedfordshire MP's comments that she was appearing on the programme to highlight her views on abortion time limits was "a shabby excuse" and "the worst thing of all".
Louise Mensch said she had "no fear" of defeat at the next general election after her husband told The Sunday Times (£) that was the motivation for her resigning as a Tory MP.
There was a mixed reaction on the streets of Corby to the news that Conservative MP Louise Mensch is stepping down.
While some residents said it was a "sad loss," others claimed Mensch was hardly seen in her Corby and East Northamptonshire constituency.
"We never see her basically," one said. "The only time we saw her was in the papers or on the news."
After news that Louise Mensch is to resign as MP for Corby and East Northamptonshire, Boris Johnson is quizzed on whether he'd consider standing in the byelection.
Andy Sawford, Labour's Prospective ParliamentaryCandidate for Corby and East Northamptonshire has said that Louise Mensch was "obviously struggling to balance being MP with her family and business commitments."