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."
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."
Labour is now looking forward to the campaign ahead, fighting for action on jobs and the economy, supporting our local services which are facing massive cuts and working with local community organisations.
During the by-election we will focus on the two wasted years of Tory policies that have taken the country back into recession and left Corby suffering job losses in both the public and private sector.
This will be a tough election for Labour but we are determined to hold this Tory-led Government to account by showing the disastrous impact of their polices on the people of Corby.
– Andy Sawford, Labour Prospective Parliamentary Candidate for Corby and East Northamptonshire