The article, which is the first of its kind for the European Union, suggests that if a country wants to leave the EU, it has to notify the Council, which will decide, by qualified majority, the terms of the agreement.

German socialist MP, Jürgen Meyer, argued that this article could be used as a continuous threat by national parliaments when they contested an EU decision, while French government representative, Pascale Andreani, felt that "unilateral right of retreat" would make the Union more fragile.

Socialist MEP, Anne van Lancker, argued strongly that Europe is "not an ordinary international organisation" and so the rules governing withdrawal should be more strict and countries should only be able to leave under "extraordinary circumstances."

EU is not a prison

The European Union is not a prison, argued others. Scottish MEP, Neil McCormick, said "it is important that people know that the Union is voluntary and a possibility exists to leave."

Irish government representative, Dick Roche, said the exit clause would be the best answer to euroscepticism, while the Estonian representative Henrik Hololei said such a clause would be useful for encouraging citizens to accept the constitutional treaty.

Comings and goings

Delegates were also unable to agree on the second part of the proposed article, which suggests that - if no agreement can be reached on the terms of withdrawal - the Constitution will automatically cease to apply, two years after the withdrawal request.

The Union is not a station hall," said French MP, Hubert Haenel, highlighting the fear that unless a fixed agreement is reached between the two sides, governments could change their minds about wanting to leave the EU.