Public unhappiness with the European Union is "the deepest it has ever been", William Hague will say on Tuesday.
The Foreign Secretary will warn European governments, including Germany, that British opinions over the EU are hardening, suggesting the current settlement is becoming "unsustainable".
Mr Hague will make his comments in Berlin, amid tensions between Britain and Germany over Europe and in particular the EU budget. Angela Merkel, the German chancellor, is said to be irritated by the increasingly strident stance of David Cameron's administration. The Prime Minister yesterday insisted Britain would "stick to our guns" on his promise to freeze the EU budget.