European Commission chief Jean-Claude Juncker refused Tuesday to entertain the idea of a British exit from the European Union, saying there is "no plan B" ahead of talks with British Prime Minister David Cameron.

"If I would say now that we have a plan B, this would indicate a kind of willingness of the commission to envisage seriously that Britain could leave the European Union," Juncker said. "So I am not entering into the details of a plan B, because we don't have a plan B, we have a plan A."