EU leaders are to meet to discuss the UK's "divorce" from the organisation after a historic referendum result.
The UK voted by 52% to 48% to leave the EU. Prime Minister David Cameron has said he will step down by October.
The first meeting of EU leaders with no British representation will be held on Wednesday. The EU has urged the UK to start negotiations to leave quickly.
European Commission head Jean-Claude Juncker stressed the "Union of the remaining 27 members will continue".