MPs have decided to hold a new inquiry into allegations that some of their phones were hacked by journalists at the News of the World.
The cross-party Committee on Standards and Privileges will investigate whether MPs' phones were targeted, after Labour MP Chris Bryant claimed that such practices would amount to "contempt of Parliament".
Speaker John Bercow granted an emergency debate on the allegations on 9 September 2010.
At the end of the debate, MPs backed without a vote Mr Bryant's call for the matter to be referred to the committee.
Mr Bryant told the Commons he was one of the MPs who had contacted the Metropolitan Police, and was subsequently told that he was on a list of those allegedly targeted by private investigator Glenn Mulcaire.
He said he suspected that was the "tip of the iceberg" and hacking extended not just to Labour MPs but also to Liberal Democrats and Tories.
The row centres on the period when No 10 director of communications Andy Coulson edited the News of the World, although Mr Bryant insisted that his call for the committee to investigate was "not about one man".
Mr Coulson has always denied any knowledge of illegal eavesdropping at the News of the World, for which Mr Mulcaire and the paper's ex-royal editor Clive Goodman were jailed in 2007.
West Bromwich East MP Mr Watson, a member of the culture, media and sport select committee, told MPs: "Something very dark lurks in the evidence files of the Mulcaire case, and dark and mysterious forces are keeping it that way."
He urged the standards and privileges committee to call News International founder Rupert Murdoch as a witness, calling on MPs to take a stand against the media.
"They, the barons of the media with their red-topped assassins, are the biggest beasts in the modern jungle. They have no predators, they are untouchable, they laugh at the law, they sneer at Parliament, they have the power to hurt us and they do with gusto and precision.
"The most powerful people in the land - prime ministers, ministers and MPs of every party - are guilty in their own way of perpetuating a media culture that allows the characters of the decent to be traduced out of casual malice, for money, for spite, for sport, for any reason they like," he added.