MEPs seek change to Lisbon Treaty to accommodate new colleagues

"The European Council now has a green light to take the decision next June in a brief Intergovernmental Conference," said Mr Mendez de Vigo. "We are not going to call for a Convention beforehand as this is a transitional and exceptional measure that will not constitute, in any way, a precedent for the future."

Elections to the European chamber were held last June under the EU's old rulebook, the Nice Treaty, which sets the number of MEPs at 736. But the eventual completion by member states of a hugely drawn out ratification process late last year ushered in Lisbon Treaty rules on 1 December 2009, allowing for 751 MEPs.

With the next European elections not until 2014, an EU Treaty change is necessary to allow the additional deputies to join beforehand.

Set to gain four new members in the increasingly powerful European legislature, the Spanish government, current holders of the EU's rotating presidency, is particularly keen to see the number of MEPs quickly increased.

Austria, France and Sweden are set to get two extra seats, while Bulgaria, Italy, Latvia, Malta, the Netherlands, Poland, Slovenia and the United Kingdom will all receive one more.

Germany is the only country set to lose seats, but the pruning of three of its MEPs will not take place before the next European elections, meaning the number of MEPs will temporary swell to 754, once all the legal hurdles have been overcome.

MEPs sitting in plenary this May are expected to endorse the constitutional committee's decision, but any treaty changes agreed at an Intergovernmental Conference would still need to be ratified in each of the EU's 27 member states, a process that could potentially take several years.

With a UK general election scheduled for 6 May, the country's Conservatives have pledged to hold a referendum on any future EU treaty changes.

A reopening of EU rules would also allow for additional changes at the same time, with Germany's Angela Merkel recently indicating her desire to toughen up the bloc's laws on budgetary spending.

Changes to allow the extra 18 deputies to join the chamber might also be combined with those needed to enable Croatia to join the EU, scheduled for 2012.

In the intervening period however, it is unclear what the fate the incoming lawmakers will be, with observer status in the European Parliament one possible option.