The vice-president of the European Commission, and competition commissioner, Joaquin Almunia has warned that it would be a "disaster" for the UK if it withdrew from the EU.
He told BBC's HARDtalk that David Cameron's hopes of renegotiating the UK's terms of membership would also be "extremely difficult".
You can watch the full interview on the BBC News Channel on Tuesday 15 January at 04:30 GMT and Wednesday 16 January at 00:30 GMT and on BBC World News on Tuesday 15 January at 04:30, 09:30, 14:30 and 21:30 GMT.
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