Prime Minister David Cameron held talks on Wednesday with potential allies in the European Union as he seeks to avoid isolation after vetoing EU treaty changes to allow closer fiscal union by euro zone members.

Britain, the EU's third largest economy, was left on its own when 26 of the 27 member states led by Germany and France agreed on December 9 to press ahead with a separate treaty for deeper economic integration to save the euro currency.

Cameron, who vetoed an EU-wide agreement after failing to win safeguards he had sought for Britain's important financial services industry, has held phone conversations with several EU leaders in the last two days, his spokesman said.

He said Cameron spoke to Czech Prime Minister Petr Necas and Swedish Prime Minister Fredrik Reinfeldt on Wednesday and to Irish Prime Minister Enda Kenny on Tuesday.

The Czech Republic and Sweden are seen as possible waverers on a fiscal convergence deal, while Ireland is worried about a proposed pan-European financial transactions tax that could hurt its financial services industry while bypassing nearby Britain.

Cameron assured all the leaders that Britain wanted the new arrangement to succeed, but said that without the safeguards he sought it was best that the 17-member euro zone proceeded outside the EU's Lisbon Treaty, his spokesman said.

Cameron told the other leaders that Britain ... wanted to find the right way forward that preserved the proper role of the EU and its institutions as the guardian of the treaties and the single market, the spokesman added.

Non-euro zone member Britain has raised concerns about EU institutions it says are intended for all 27 states, such as the European Commission and the European Court of Justice, being used to enforce any new euro zone agreement.

COOPERATION

In each call the leaders agreed to build on their close cooperation on EU issues, especially promoting jobs and growth through the single market. They agreed that the priority for the European economy remained comprehensive and decisive action to deal with debt and increase competitiveness, Cameron's spokesman said.

Several of the non-euro zone governments that went along with the new inter-governmental plan on fiscal union, including Sweden, Hungary and the Czech Republic, still need parliamentary approval before they can give their full backing to the move.

Sweden said on Tuesday it was uncertain about signing up to the pact, raising the possibility of it joining Britain on the sidelines.

Ireland warned on Wednesday its financial services industry may be at risk from Britain's opt-out. Britain's decision could also cause political problems for the Irish government, which is keen to avoid putting its participation in the new fiscal union to a referendum.

Cameron also held a private meeting on Wednesday evening with legislators from his centre-right Conservative Party.

Members of Cameron's largely eurosceptic party were pleased with his veto but it has caused a rift with his junior coalition partner, the pro-European Liberal Democrats.

The Guardian newspaper quoted one senior Conservative as saying Cameron told the meeting that there was no question of there being 26 EU member states against Britain.

There are a number of countries that are not all sure what they are being asked to sign up to, the source was quoted as saying. A spokesman for Cameron declined comment.

(Reporting by Adrian Croft; Editing by Mark Heinrich)