British Prime Minister Tony Blair warned Tuesday that it would be a serious mistake for the European Union to turn its back on Turkey, voicing hope for progress at an EU summit this week.

"It in my view would be a very big long-term stategic mistake for Europe to turn its back on Turkey," he told reporters, ahead of an EU summit in Brussels opening Thursday.

Blair, one of Turkey's strongest supporters within the 25-nation European bloc, was speaking after EU foreign ministers decided to slow down its troubled accession talks, a move denounced in Ankara as "unfair".

EU leaders in Brussels could either rubber stamp the ministers' decision, but Blair indicated that he may press his European counterparts to give even more ground on the issue.

"I hope that we can make progress on the various issues to do with the Ankara Agreement and so on in the time to come," he said, referring to a customs accord between Turkey and the European Union which Ankara is accused of breaching.

Turkey, whose forces invaded the northern part of Cyprus in 1974, has until recently refused to allow Cypriot planes and ships to use its airports and ports, in what the EU describes as a violation of the deal.

"I understand all the short-term political difficulties in European countries," Blair said.

But he added: "I hope that we can get through Friday's (EU summit) now satisfactorily and then regain momentum, and that's what we will be working for."