Gordon Brown has won the support of European finance ministers for the draft European constitution to be toughened so that key decisions on taxation can be taken only by unanimous voting.

At a meeting in Brussels the chancellor said: "We have our clear red lines. They have not changed at all."

He added: "They are that we cannot accept a move away from unanimity on tax decisions, or move towards a federal fiscal policy.

"We will also insist on our red lines on social security, foreign policy and defence and security."