The Liberal Democrats have walked out of the House of Commons after their calls for a referendum on Europe were rejected.
Angry exchanges broke out between Lib Dem MPs and the deputy speaker of the House of Commons after they were informed an amendment calling for a referendum on Britain's future in the EU would not be put before the house.
Lib Dem foreign affairs spokesman Ed Davey was expelled from the Commons after declaring the ruling was "outrageous" and his fellow Liberal Democrats walked out in protest.
Immediately before their exodus the Lib Dems were accused of trying to shout down the deputy speaker in a major breach of parliamentary procedure.
MPs are currently debating the Lisbon treaty and Lib Dem leader Nick Clegg confirmed yesterday his party would use the opportunity to push for a wider debate on Britain's role in Europe.
Mr Clegg said the refusal today to allow a vote was an "outrage".
He said: "To allow a vote on a restrictive treaty referendum but deny one on the real issue of our membership of the EU is absurd.
"It is like allowing the British public to choose their mode of travel without asking whether they actually want to continue on the journey at all."
The Lib Dem leader accused Labour and the Conservatives of "colluding" to steer the debate away from the wider issue of Britain in the EU.
Mr Clegg continued: "The Labour party is terrified of an open debate, whilst David Cameron's Conservatives are focusing on the sideshow of a referendum on the technical details of the Lisbon treaty.
"It's time for the Westminster establishment to stop being so cowardly over Europe and have an open debate with the country. I will be proud to lead the Liberal Democrats in arguing the case for our membership of the EU."