Nick Clegg says it is right to abstain from the vote
Liberal Democrat leader Nick Clegg has defended ordering his party to abstain from a Commons vote on holding a referendum on the new EU treaty.
He said most Lib Dem MPs wanted a referendum on Britain's membership of the EU, not on the Lisbon Treaty.
Mr Clegg told BBC's Newsnight: "People should have a say, but not on the restrictive question of the treaty."
However the Tories say the treaty is effectively a new constitution and so a referendum is needed.
On Wednesday, MPs are set to vote on a Tory amendment calling for a referendum on the treaty as part of an EU debate.
Mr Clegg said it was right for the party not to take part because the amendment did "not get to the heart of the matter which is our fundamental relationship with the European Union".
He told Newsnight the government did not believe in a referendum, and the Conservatives were "pulling the wool" over the public's eyes by demanding something which "would not change the European Union a jot".
"When presented with only one question, it seems to be perfectly consistent for us to say the best way to express yes to a referendum, no to that question is to abstain," he said.
He said none of his MPs had promised a referendum on the Lisbon Treaty because it did not exist during the last election, and he also denied reports he had told MPs to resign if they did not follow the three-line whip.
On Tuesday, MPs overwhelmingly rejected a Lib Dem attempt to force a debate on the wider issue of Britain's EU membership after a decision by the Commons Speaker last week not to allow a debate prompted a mass walkout of the party's MPs.
Tory leader David Cameron has appealed to Lib Dem MPs to rebel against their party leadership.
His party has said Mr Clegg is trying to "paper over" his party's divisions over a separate referendum on the EU treaty.
And senior Tory Sir Patrick Cormack attacked the Lib Dem motion as an "extraordinary example of sanctimonious chicanery".
For the government, Europe Minister Jim Murphy said the Lib Dem vote was not needed, as the same issue had already been heavily defeated in a Commons vote last November by 68 to 464 votes.
He added the debate on Wednesday was on the "merits of the Lisbon Treaty not whether we should or should not be in the European Union".
"Some commentators - unfairly I'm sure - have said that this instruction isn't so much about the inner detail of the Lisbon treaty, but the inner dynamic of the Liberal Democratic party," he added.
But Labour MP Andrew MacKinlay said he would vote for the debate and said he believed the pro-Europeans would win an "in or out" referendum and it would reaffirm Britain's place in the EU.
He added: "Members of the flat earth society and all those who peddle the most God almighty nonsense about this would be quashed."
The Lisbon Treaty was designed to replace the EU constitution, on which all three of the main parties promised a referendum in their 2005 manifestos.
But the constitution was rejected by French and Dutch voters in 2005.
The government and the Lib Dems say the treaty does not have constitutional implications, so a referendum on it is not needed.
But the Conservatives, some Labour and Lib Dem MPs and the UK Independence Party, all say that it is effectively the constitution under a different name - so there should be a referendum.
Wednesday's vote in the House of Commons - expected in the early evening - is seen as the key vote in the EU treaty's progress through the UK Parliament.
Conservative leader David Cameron says he hopes they can win - but said "a lot depends" on support from rebel Lib Dem MPs.