The European Parliament's centre-right grouping has declared war on David Cameron and said a new Conservative government must not be allowed to derail the Lisbon Treaty.

The Tory leader has angered the European People's Party (EPP) after pulling out of the grouping to form a new Eurosceptic bloc called the European Conservatives and Reformists.

Mr Cameron's pledge to hold a referendum on the Lisbon European Union Treaty, if it remains unratified by the Irish by the time of a British general election, has also alarmed the Brussels establishment as Labour goes into political meltdown.