Media playback is unsupported on your device Media caption Tom Watson on new phone-hacking threats

The editor of The Sun should be asked if the newspaper had any involvement in phone hacking, a Labour MP has said.

Tom Watson, a leading campaigner on the issue, suggested it was "only a matter of time" before the News International owned paper was linked to the scandal.

"Do you really think hacking only happened on the News of the World?" he asked the Labour Party conference.

Police have questioned scores of former News of the World staff but have not brought any charges to date.

Mr Watson used a debate on the phone hacking scandal to suggest that the practice had not been confined to the News of the World, which was closed down in July.

'Contagion'

He said: "Do you really think hacking only happened on the News of the World? Ask Dominic Mohan. He is the current editor of the Sun.

There should also have been an element of shame because for years we were complicit in propping up Murdoch's power Len McCluskey, Unite union

"He used to joke about lax security at Vodafone when he attended celebrity parties.

"Ask the editor of the Sun if he thinks Rupert Murdoch's contagion has spread to other newspapers.

"Ask him, and if he gives you an honest answer, he will tell you that it is only a matter of time before we find the Sun in the evidence file of the convicted private investigator that hacked Milly Dowler's phone."

Mr Mohan became editor of the Sun in 2009, having previously been deputy editor and features editor. He briefly worked at the News of the World in the mid-1990s.

The former chief executive of News International Rebekah Brooks, one of those questioned by police as part of their investigation, has insisted that The Sun was a "clean ship" when she was editor between 2003 and 2009.

Murdoch criticism

Mr Watson also launched a fierce attack on News International chairman James Murdoch, who has been recalled to answer futher questions by the Commons media committee about what he knew about the extent of phone hacking

Mr Murdoch has insisted he was not shown evidence indicating that hacking was wider than the company acknowledged at the time, despite conflicting claims from other staff.

But Mr Watson said Mr Murdoch was "certainly not a fit and proper person" to be chairman of a major broadcaster such as BSkyB and also called into question whether the Murdoch-controlled News Corporation could continue to own shares in the broadcaster.

"It is a company sick with corruption and criminality from top to bottom," he said. "That much has been proved. The Murdochs and their minions have consistently and blatantly lied to our courts and our Parliament."

A number of speakers also criticised past Labour governments for getting too close to the Murdoch-owned press.

"For our party, there should also have been an element of shame because for years we were complicit in propping up Murdoch's power," Len McCluskey, head of the Unite union, told delegates.

And former Labour minister Chris Bryant said the party "should choose our bedfellows with a little more care" in future.

The police have arrested 16 people to date as part of their investigation into alleged hacking at the News of the World. Parent firm News International is also conducting an internal inquiry into practices at the group.

A News International spokesperson said: "Everyone should act responsibly regarding the current investigations to allow the police to get on with their important work.

"If Mr Watson has specific information he should immediately hand it to the police and we urge him to do so.

"We are not aware of any evidence that The Sun engaged in activity as suggested by Mr Watson."