Every single member of the parliamentary committee investigating phone hacking was followed for three days by private investigators and staff at News of the World as recently as February, it has been claimed.
The dramatic new development comes from media commentator Roy Greenslade who made the comments on Media Matters Radio.
"I do have a source who was at News of the World… he tells me that for three days, only six, seven months ago, every single member of the parliamentary committee investigating this matter were followed by private eyes and or members of staff at the newspaper.
"Only after some of the staff protested that they didn't want to do it were they called off.
"That goes even beyond what we previously heard and I've only just been told this in the last 24 hours. I wish I could name the source but I have it confidentially."
Tom Watson MP, who sits on the committee and this week described James Murdoch as a member of the Mafia, told The Huffington Post UK: "I'm staggered. When will this company know the game is up?"
Last week the use of private investigators by the now defunct newspaper hit the headlines after it emerged Mark Lewis, the lawyer central to fighting phone hacking, and his family were followed.
Tom Watson, Louise Mensch, Steve Rotheram and chairman John Whittingdale are perhaps the highest profile MPs on the culture, media and sport committee.
The other MPs on the committee are: Damian Collins (Con), Philip Davis (Con), Paul Farrelly (Lab), Alan Keen (Lab), Thérèse Coffey (Con), Jim Sheridan (Lab) and Adrian Sanders (Lib Dem).
Members have changed little on the committee in the last six months. In May, following the death of Labour MP David Cairns, Cathy Jamieson sat on the committee.
After she was promoted to the Labour front bench Jamieson was replaced in October with Liverpool Walton MP Rotheram.