Prime Minister David Cameron will finally deliver his long-awaited speech on Britain's future in the European Union in London on Wednesday.
Mr Cameron was forced to call off plans to make the address - at least six months in the preparation - in Amsterdam last Friday because of the hostage crisis in Algeria.
Extracts released last week showed that he will use the speech to warn EU leaders that Britain could leave the 27-nation bloc if three key concerns are not resolved.
But his official spokesman declined to comment on weekend press reports that he will announce an in/out referendum to be held after the 2015 general election, but rule out legislation during this parliament.
According to advance extracts released last week, Mr Cameron will warn that Britain could "drift towards the exit" from the EU unless there is real change in Brussels.
He identified the crisis in the eurozone, the challenge of economic competitiveness and the issue of democratic legitimacy as key issues which must be resolved in negotiations on the future shape of the EU.
Mr Cameron has indicated he wants to renegotiate the UK's relationship with the EU and then seek "fresh consent" for the new arrangement from the British people - probably through a referendum some time after the next general election. He has yet to make clear what the terms of the referendum would be.
It is understood that Mr Cameron initially planned to give the speech in Amsterdam on Tuesday, but had to abandon that date because it clashed with German and French celebrations of the 50th anniversary of the 1963 Elysee Treaty sealing post-war reconciliation.
Asked why Mr Cameron would now be delivering his speech in London, his spokesman said: "We were planning to give it in Amsterdam. Unfortunately, that didn't prove possible and Wednesday morning in London fits better with the Prime Minister's schedule."
The spokesman added: "There is a debate going on across the EU. There is also an active debate going on here in the UK. The Prime Minister's speech will be reflecting both those aspects."