WARSAW (Reuters) - Poland, the biggest recipient of European Union funds, would seek common ground with countries that pay the most into EU coffers if a long-term budget proposal is vetoed, Prime Minister Donald Tusk said on Friday.

EU negotiators remain hopeful of an agreement on the bloc's next budget, despite differences of opinion between Germany, Britain and other major financial contributors.

But if there was no deal, the current EU budget would remain in force provisionally on a monthly basis adjusted for inflation, but long-term projects may be difficult or impossible to finance without special provisions approved by the bloc.

Tusk said a veto at what is expected to be a marathon summit later this month was a possibility, although he warned it should be "the absolute last resort" because some kind of a spending plan must be in place early next year.

"In case of plan B, a coalition with large net contributors will be important to ensure that the provisional budget is also applied to Poland," Tusk said in a speech to parliament.

Tusk said a large budget without "exaggerated cuts" was in the interest of both the entire bloc and Poland because it would boost growth, employment and competitiveness.

"It seems unlikely a common point of view can be achieved in this debate with the British," Tusk said. "Their point of view is not for a strong, developing Europe with a large budget in common with our national interest."

British Prime Minister David Cameron had threatened a veto at the November 22-23 summit unless London's demands to freeze EU spending in real terms are met.

Sweden, Germany and Britain have demanded cuts of 100-200 billion euros to the European Commission's proposed 1 trillion euro total, slightly more than 1 percent of the 27-nation bloc's gross domestic product. By contrast national government spending accounts for between 40 and 56 percent of member states' GDP.

Tusk said his government would approve the EU fiscal pact at its next sitting and would forward it to the parliament to make sure Poland, which remains committed to joining the euro zone, keeps a seat at the table in talks about the bloc's future.

(Reporting by Pawel Sobczak; writing by Chris Borowski; Editing by Catherine Evans)