Top European Union officials are due to attended a ceremony to mark the coming into force of the Lisbon Treaty, which is designed to ensure the bloc has more say in world affairs.

The treaty took effect Tuesday after years of wrangling in the 27-nation union over its provisions.

It features new rules to accelerate decision-making so the EU can respond more swiftly to global issues.

The ceremony was taking place in the Portuguese capital, where the treaty was signed two years ago.

Expected at the event were Catherine Ashton, Europe's new foreign policy chief, Belgium's Herman van Rompuy who becomes the first EU president on Jan. 1, and European Commission President Jose Manuel Barroso.