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.
Piers Morgan has confirmed he was questioned by police about phone hacking at the Mirror newspaper group - although it is not the first he has been linked to the hacking scandal.
In his memoirs, published in 2003, the former Daily Mirror editor appeared to suggest he knew all about phone hacking, and he then repeated those stories to the media when he gave interviews.
Then he appeared before Lord Leveson at his inquiry in late 2012, and said that absolutely no hacking took place under his editorship at the Daily Mirror, going back on all those earlier suggestions.
Morgan is now based in the US, but flew back to the UK in December to be questioned by police, after being approached by officers belonging to Operation Golding which was set up to look into voice message interception.
The Mirror Group deny that any kind of hacking occurred at their newspaper group.
Piers Morgan has confirmed that he was interviewed by officers investigating phone hacking in December.
Metropolitan Police said a 48-year-old journalist was "interviewed under caution", although a spokesman refused to confirm the name of the individual.
In a statement to The Guardian through a spokesperson, Mr Morgan said:
In early November I was asked to attend an interview by officers from Operation Weeting when I was next in the UK.
This was further to a full witness statement I had already freely provided. I attended that interview as requested on 6 December 2013.
Morgan, who is now a presenter on CNN, was editor of the Daily Mirror from 1995 until 2004.
Former Daily Mirror editor Piers Morgan has been questioned under caution about phone hacking, Press Association sources have confirmed.
"A 48-year-old man, a journalist, was interviewed under caution on 6 December 2013 by officers from Operation Golding in connection with suspected conspiracy to intercept telephone voicemails," a Metropolitan Police spokesman told ITV News.
"He was interviewed by appointment at a south London police station. He was not arrested."
Politicians at Westminster have been warned not to comment in public on upcoming trials over newspaper phone hacking.
The case has been at the centre of political debate for more than two years, but Solicitor General Oliver Heald has acted to counter the risk of commentary prejudicing the proceedings, which are expected to last for several months.
Parliamentary privilege means a politician can theoretically talk about a live case in the House of Commons without fear of prosecution.
Former News of the World deputy editor Neil Wallis said he is "glad" that Rupert Murdoch "stood by his staff" after hearing secret audio recordings made during a News Corp meeting.
Phone-hacking charges against Mr Wallis were dropped in February this year.
He also replied to a Twitter user who asked whether he thought Murdoch was "really backing the staff":
In one clip from a secret audio recording obtained by Channel 4 News, Rupert Murdoch is heard branding police "totally incompetent" and damning the Scotland Yard inquiry into corrupt payments to public officials.
"It's the biggest inquiry ever, over next to nothing," he says.
Hear more of the recordings at Channel 4 News.
A News Corp statement said Mr Murdoch was showing "understandable empathy" to his staff.
Defending Rupert Murdoch's pledge to staff, a spokesman for News Corp told Channel 4 News:
No other company has done as much to identify what went wrong, compensate the victims, and ensure the same mistakes do not happen again.
The unprecedented co-operation granted by News Corp was agreed unanimously by senior management and the board, and the MSC continues to co-operate under the supervision of the courts.
Rupert Murdoch has shown understandable empathy with the staff and families affected and will assume they are innocent until and unless proven guilty.
An MP has called for police action after Rupert Murdoch was apparently recorded telling journalists he regretted the level of cooperation over phone-hacking and illegal payments.
Labour MP Tom Watson called for police to question Mr Murdoch over the alleged comments, telling Channel 4 News:
What I would like to know is what are they sitting on that they've not given the police. And I'm sure that this transcript and this audiotape should be in the hands of the police tomorrow because I hope that they're going to be interviewing Rupert Murdoch about what he did know about criminality in his organisation ...
Rupert Murdoch told Parliament one thing and told his staff another. He told Parliament that he was fully co-operating with the police, he told his staff that it was a mistake they were co-operating with the police.
Rupert Murdoch also appears to suggest in the recording, broadcast by Channel 4 News, that any journalists who were convicted and jailed in connection with the phone-hacking inquiry could get their jobs back. He is heard saying:
I will do everything in my power to give you total support, even if you're convicted and get six months or whatever.
You're all innocent until proven guilty. What you're asking is: what happens if some of you are proven guilty? What afterwards?
I'm not allowed to promise you - I will promise you continued health support - but your jobs. I've got to be careful what comes out - but, frankly, I won't say it, but just trust me.
A spokesman for News Corp told Channel 4 News: "Rupert Murdoch has shown understandable empathy with the staff and families affected and will assume they are innocent until and unless proven guilty."