The European Union was plunged into political crisis on Friday night after Britain led the way in blocking a proposed deal on the new seven-year budget.

Tony Blair, the UK prime minister, was one of a minority of leaders who refused to accept a compromise package, as the Brussels summit collapsed in acrimony shortly before midnight. The failure of the talks means the transfer of billions of euros of aid to former communist countries in eastern Europe, due to start on January 1 2007, may be delayed.