Britain's membership of the European Union has become a "worsening deal" according to a top Harvard professor.

Robert Barro said it would be "amazing" if the UK were to "seriously consider voting in favour" of the new constitution.

Meanwhile, Europe minister Denis MacShane has said that the government had created a problem for itself in "making the euro a litmus test for being good Europeans".

MacShane also dismissed the euro as "this damn currency" and added, in an interview with the New Statesman, that he would never have voted to join it during the first years of the Labour government because of its exchange rate with sterling.