Tony Blair has ruled out a referendum on a new treaty to reform the European Union as ministers prepare for intense negotiations ahead of next week's EU summit.

Mr Blair had pledged to hold a referendum on the planned EU constitution in 2004 before the document was rejected by voters in France and Holland.

Yesterday No 10 insisted that the agreement expected to be sealed next week would lead only to an "amending treaty" that did not need to be approved at the polls.

But the Conservatives insisted that major reform of the EU should be approved by a referendum.

The German Chancellor Angela Merkel, who will chair the summit, is pressing for a deal which preserves much of the changes in the constitutional treaty, which floundered two years ago.

But Mr Blair's spokesman insisted: "This treaty should be an amending treaty. Previous amending treaties have not required a referendum and we do not believe that this treaty should have the characteristics of a constitution."