The former defence secretary, Dr Liam Fox, is giving a speech calling for a referendum on Britain's relationship with the European Union.
He has said: "I do not think national interest served by the current EU relationship".
He has also told the audience at the Taxpayers' Alliance function: "Too often EU leaders behave as though they are at the centre of the global economy".
Former defence secretary Liam Fox has said that the UK should leave the European Union unless there is a rebalancing of their relationship.
Foreign Secretary Hague said there would be a "very, very powerful" case for a referendum if Europe moved towards a more federal system.