Senior civil servants have been warned to expect a "snap announcement" on the euro well before the government's June deadline for deciding whether to recommend joining the single currency, according to today's Telegraph.

A decision is likely to be made "sooner rather than later" to avoid a build-up of speculation in the run-up to June 7, the last date by which the government has said it will give its verdict.

The paper quotes one government insider as saying: "There are as many options on the table as there are weeks until June. But they'll go early and before June."

A foreign policy think tank has warned the decision is likely to be negative as public opinion is unlikely to change in the foreseeable future.

The Foreign Policy Centre said in a report that the task for pro-euro campaigners was "difficult" and questioned whether negative poll findings could be turned around.