Four Labour MPs who are campaigning for a referendum on the EU treaty, against government policy, received a hostile reception at a party meeting.
A 15ft (4.5m) inflatable ballot box was used to launch the campaign
Frank Field, Kate Hoey, Gisela Stuart and Graham Stringer were criticised for "uncomradely behaviour" at a meeting of the Parliamentary Labour Party.
They are part of a campaign which plans to hold unofficial polls in marginal Labour seats for a referendum.
They were referred to a senior MPs' committee and face disciplinary action.
The four MPs had already been reprimanded by chief whip Geoff Hoon over their part in the I Want A Referendum (IWAR) Campaign.
On Sunday Mr Field, a former minister, said he had been "shouted at" by Mr Hoon and accused the party leadership of "ineptness" for "trying to expel people from the Parliamentary Labour Party for keeping their election promises".
A spokesman for Mr Hoon said earlier: "For Labour MPs to deliberately target fellow Labour MPs to undermine them in their own constituencies is completely unacceptable."
IWAR is organising unofficial referendums in 10 marginal constituencies - including the East Renfrewshire seat held by Europe minister Jim Murphy - to put pressure on Prime Minister Gordon Brown.
But Mr Field and Ms Hoey's names are to be removed from literature distributed in that area "on pain of formal disciplinary action", a spokesman for IWAR said.
The BBC understands that Mr Stringer has said he will withdraw from IWAR's advisory board.
The Conservatives and UKIP have been campaigning hard for a referendum on the new Lisbon treaty - signed by Gordon Brown and other EU leaders in December, which needs to be ratified by Parliament.
Tory MPs are fighting it in the Commons, where the bill which would ratify it is being debated this month.
But some Labour MPs - and trade unions - also believe there should be a referendum, because Labour promised one on the EU Constitution in its 2005 manifesto.
The constitution failed when it was rejected by French and Dutch voters at referendums, and the treaty aims to replace it.
But the government says it is a very different treaty and a referendum is not necessary. It says most changes are minor and procedural and it has secured "opt-outs" where necessary.