Business secretary Vince Cable has blasted the European Union referendum as a "serious distraction" that will damage the British economy.
Ahead of a vote by lawmakers on Tory James Wharton's private members bill calling for an in/out referendum, Cable launched an assault on his Conservative partners in the coalition government at an event by Business for New Europe, a lobby group pushing the case to keep the UK in the 28-member EU.
"It's a serious distraction. We are recovering from the worst economic crisis for the best part of a century, the last thing we need now is massive levels of uncertainty in the business community," said Cable.
Wharton introduced the bill to try and secure an EU referendum in law after Prime Minister David Cameron said he would hold a vote if the Conservatives won the next election. However, the vote will not bind the next parliament and could be repealed by the victorious party.
Cameron insists he wants to stay in the EU, but that the UK's continued membership should be put to a popular vote in 2017.
He wants to use the threat of a UK-exit to renegotiate the country's position in the EU by securing treaty changes, but leaders on the continent have warned him that the terms of membership are "not an a-la-carte menu".
The Tory leader has been under pressure over the EU from many of his euro sceptic backbenchers, who are relishing their first real opportunity to pull the UK out. To appease them further he has placed a three-line whip on Wharton's bill, ensuring it will pass the commons.
Lib Dem leader and UK deputy prime minister Nick Clegg joined Cable's attack on the Tories over the EU referendum and said he would not be ordering his MPs to vote on the bill, declaring the party would not "waste any of our time helping the Conservatives indulge in their own internal feuds".
"The Liberal Democrats have been consistent throughout. The Conservatives have changed," he said.
"They now want to pluck a slightly arbitrary date in the diary out of thin air to have a referendum on a very ill-defined process of so-called renegotiation."
Labour has not made it clear on its EU referendum position. The party has traditionally been in favour of the EU, with former Prime Minister Tony Blair even wanting to sign the UK up to the eurozone. However its MPs have been urged by Labour whips to abstain on Wharton's bill.
The EU single market is the UK's biggest trading partner. It accounts for around 52% of British trade in goods and services, which in 2011 alone was worth £358bn (€418bn, $545bn).