The Liberal Democrats have indicated they could back a Labour move in parliament to delay the Murdoch takeover of BSkyB until after the police investigations into phone hacking.

Labour is preparing to table a motion to force the government to suspend the takeover amid a furore over News International's journalistic practices.

Ed Milband said the bid could not go ahead based only on assurances given by News International, after the company had lied to the Press Complaints Commission. John Yates, assistant commissioner at Scotland Yard, accused News International of having covered up the "industrial scale" of hacking at the News of the World.

Chris Huhne, the energy secretary, and Simon Hughes, Liberal Democrat deputy leader, both indicated that the party could back the Labour motion if it was not seen as too "partisan". If the Lib Dems were to join Labour, it could pose a challenge for the coalition – although there were some suggestions that the Tories could join the move in the face of fierce public opposition to the merger.

Philip Hammond, the transport secretary, told Sky News: "I understand people would be very concerned [if the takeover went through while criminal investigations were ongoing] and I think many of us would be very concerned.

"But we have to operate within the law. If the motion is calling on the government to ignore its duties under the law, simply to ride roughshod over the law, then I'm afraid that would be calling on us to be in no better position than others are currently being accused of."

Miliband told the BBC's Andrew Marr Show: "We've seen this week the head of the Press Complaints Commission say she was lied to by News Corporation. We are expected to believe from Jeremy Hunt [the culture secretary] that he can go ahead with this process, this takeover of BSkyB, on the basis of assurances from the NC. I don't believe that's acceptable.

"I say this to the prime minister candidly. Over the next 72 hours I hope he changes his position on this, because I don't want to force this to a vote in the house of Commons, but I think he's got to understand that when the public have seen the disgusting revelations that we've seen this week, the idea that this organisation – which engaged in these terrible practices – should be allowed to get that 100% stake without the criminal investigation being completed and on the basis of assurances from that self-same organisation, I'm afraid that won't wash with the public."

Hughes told Sky News: "We have to be careful and I would suggest if Labour want our support they should come and talk to us about that. If a motion can be formed that can provide wider than Labour support and isn't a partisan motion, then I would think that they would get wider support. My recommendation to my colleagues – it's not my final decision, it's a parliamentary party decision – would be that we as a parliamentary party make clear that it's our view that the takeover should not go ahead until the criminal investigations are completed."

Huhne said on the BBC: "We will obviously have to look at the details of the motion before deciding what should be done in terms of the voting."

Labour could reveal the details of the motion on Monday and a senior source said it would be written to ensure "as much cross-party support as possible".

It is understood that the business secretary, Vince Cable – who was stripped of his responsibility for the BSkyB decision after a Telegraph sting recorded him saying he had "declared war" on Murdoch – is struggling to see how the deal can go ahead amid the police inquiries.

But the Lib Dems are adamant that any move is not seen as a Labour one, with insiders highlighting Labour's relationship with News International over the years and Miliband's failure to speak out on the issue before the Guardian revelations about the hacking of Milly Dowler's voicemail this week.

Lord Oakeshott, the Liberal Democrat peer and close ally of Cable, said: "Liberal Democrats from the cabinet to councillors to Focus deliverers are totally united. We want to block the BSkyB bid and then break up the Murdoch empire.

"He's far too powerful – we don't let Tesco have 40% of the market. This is not just about blocking the bid, it's about ending a serious danger to our democracy."

Huhne also confirmed publicly for the first time that the Liberal Democrat leader, Nick Clegg, had warned Cameron of the risks of hiring the former News of the World editor Andy Coulson as his director of communications in the days after the coalition was formed last year.

Huhne said: "I certainly raised it with Nick, and Nick raised it with the prime minister, and it was made very clear to us that this was a personal appointment of the prime minister and wasn't a government app[ointment] and therefore we didn't have any standing to object to it. It was very clear from what I had said previously that I think that big reputational risks were being run," he added.

The Observer reported that the former Lib Dem leader Lord Ashdown also warned Downing Street against Coulson's appointment days after the coalition was formed.

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