An influential German parliamentarian and ally of Chancellor Merkel has said that a renegotiation of the relationship between the EU and its member states would open up a "Pandora's box". Gunter Krichbaum, who chairs the European Affairs committee of the Bundestag, told Today presenter James Naughtie that the union, which makes up just four per cent of the global population "will have to stand together".

But the senior Conservative backbencher Bill Cash said that recent EU treaties have "only been going in one direction" and that plans, which he says aim to create a closer federal Europe, are "completely unacceptable to the British people".

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