European Commission President Jose Manuel Barroso (L) and European Council President Herman Van Rompuy hold a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium. (Xinhua/Yan Ting)

European Commission President Jose Manuel Barroso gestures during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Yan Ting)

European Council President Herman Van Rompuy speaks during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium. (Xinhua/Yan Ting)

European Commission President Jose Manuel Barroso (L) and European Council President Herman Van Rompuy hold a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Yan Ting)

European Commission President Jose Manuel Barroso speaks during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Yan Ting)

Luxembourg's Prime Minister Jean-Claude Juncker gestures during a press conference after an EU summit at the EU headquarters in Brussels, capital of Belgium, May 22, 2013. (Xinhua/Ye Pingfan)

Luxembourg's Prime Minister Jean-Claude Juncker speaks during a press conference after an EU summit at the EU headquarters in Brussels, capital of Belgium, May 22, 2013. (Xinhua/Ye Pingfan)

Italian Prime Minister Enrico Letta gestures during a press conference after an EU summit at the EU headquarters in Brussels, capital of Belgium, May 22, 2013. (Xinhua/Ye Pingfan)

Italian Prime Minister Enrico Letta speaks during a press conference after the EU summit at the EU headquarters in Brussels, capital of Belgium, May 22, 2013. (Xinhua/Ye Pingfan)

Italian Prime Minister Enrico Letta speaks during a press conference after the EU summit at the EU headquarters in Brussels, capital of Belgium, May 22, 2013. (Xinhua/Ye Pingfan)

German Chancellor Angela Merkel speaks during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Thierry Monasse)

German Chancellor Angela Merkel speaks during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Thierry Monasse)

German Chancellor Angela Merkel prepares(R, front) for a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Thierry Monasse)

French President Francois Hollande speaks during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Thierry Monasse)

British Prime Minister David Cameron speaks during a press conference at the end of an EU summit on May 22, 2013, in Brussels, capital of Belgium.(Xinhua/Thierry Monasse)