The European Commission on Tuesday welcomed the Greek parliament's ratification of the European Union's first ever constitution.

"On behalf of the Commission I welcome with great satisfaction the ratification of the European Constitution by the Greek Parliament," vice president Margot Wallstroem said in a statement.

The Greek parliament on Tuesday ratified the landmark text by 268 votes to 17. Greece thus became the sixth EU member state to ratify the new code, joining Lithuania, Hungary, Slovenia, Spain and Italy.

"We were pleased to note the overwhelming support in the vote for the Constitution. Greece once again confirmed today its European vocation," Wallstroem added.

The constitution, which aims to streamline decision-making in the expanded 25-member European Union, must be ratified by all member states.

But opinion polls suggest that France, one of the EU's largest and founding countries, may vote down the charter in a May 29 referendum, which could effectively kill the treaty.