British Prime Minister David Cameron’s letter to the European Union explaining Britain’s planned renegotiation of ties will be unveiled in the first half of next week, Europe Minister David Lidington said yesterday.

Mr Cameron will seek to defuse fellow EU leaders’ frustration over any lack of detail on the changes Britain wants and pave the way for detailed discussions with all the other member states.

“Things will become clearer, I think, for everybody when the Prime Minister’s letter to [President of the European Council] Donald Tusk is published, which I expect in the first half of next week,” Mr Lidington told reporters in the Slovak capital.

The letter will focus on four areas for negotiations in which the Britain is seeking change, he said.

Mr Cameron opposes any further transfer of sovereignty to the EU.

We need a promise of future treaty changes as far as they are legally binding and irreversible

He says British voters are unhappy with the current settlement, and wants to renegotiate relations with the bloc it joined in 1973 ahead of a referendum on membership before the end of 2017.

“There is no magic deadline” for the referendum to take place, Mr Lidington said.

“We accept that given the timescale we set it’s not practical to have a treaty change ratified in that period.

“We need a promise of future treaty changes as far as they are legally binding and irreversible.”

With British opinion polls showing a narrowing of support for staying in the EU, Mr Cameron’s government is under increasing pressure to take on Eurosceptics in both his ruling Conservative Party and the opposition Labour camp directly.