It will only underline the key political question for Britain: does the UK want to stay in the EU but in the outer circle, does it want to free itself from the EU's embrace or will it select to join a more integrated Europe?

BBC: Why Cameron is backing closer European integration

Germany says it will not allow Bulgaria or Romania to join the EU's passport-free Schengen zone if the issue is put to a vote in the EU on Thursday.

BBC: Germany mulls Schengen veto on Bulgaria and Romania

It has not wanted to join the 11 Latin American countries with free-trade deals with the world's biggest economy.

ECONOMIST: Two American giants are slowly getting to know each other