British Prime Minister David Cameron said Tuesday he would block a new European Union treaty proposed by France and Germany aimed at saving the euro, if London\'s demands are not met. He said if eurozone countries wanted to use \"European institutions\" to rescue the single currency, they would have to agree to safeguards demanded by Britain, which has not adopted the euro. Cameron has come under huge pressure from the right wing of his Conservative Party to claw back powers from Brussels if the EU were to negotiate a new treaty. \"The most important British interest right now is to sort out the problem in the eurozone that is having the chilling effect on our economy,\" said Cameron. \"That obviously means eurozone countries doing more together and if they choose to use the European treaty to do that, then obviously there will be British safeguards and British interests that I will want to insist on.\" He added: \"I won\'t sign a treaty that doesn\'t have those safeguards in it, around things like, of course, the importance of the single market and financial services.\" France and Germany said Monday they wanted a new EU treaty by March with tougher budgetary rules to deal with the debt crisis. French President Nicolas Sarkozy said the new treaty would be either for all 27 EU members or for the 17 members of the eurozone, with other nations signing on a voluntary basis. Cameron said that if eurozone countries \"choose to go ahead with a separate treaty, then clearly that is not a treaty that Britain would be signing or would be amending. \"But, of course, if they want to use the European institutions, then we will be insisting on the safeguards and the protections that Britain needs.\" The pressure on Cameron increased Monday as he faced down calls to hold a referendum on a new treaty, insisting that a public vote was unnecessary because significant powers would not be passing from London to Brussels. Under legislation passed last year, Britain must hold a referendum if such a transfer of power takes place. The issue also threatens to cause tensions with the junior partner in Cameron\'s coalition government, the pro-European Liberal Democrats.