David Cameron has denied watering down a commitment to a public veto on handing more powers to the European Union as he attempted to see off a Tory backbench rebellion.
The Prime Minister insisted that the European Union Bill, which will be the subject of a Commons vote tomorrow, represented "a manifesto pledge delivered".
Eurosceptic critics have accused the Government of a "smoke and mirrors" exercise that will do nothing to protect national sovereignty, and have tabled a series of amendments.
It was originally promised by Mr Cameron to placate MPs angry over the decision to abandon a promised public vote on the Lisbon Treaty on the grounds it was already approved. But the proposals have fallen well short of what they demand amid concerns it is loosely worded to ensure Ministers can dodge having to put changes to a referendum.
"We said in the manifesto we will make sure that if politicians try to take powers from Westminster to Brussels you, the British people, will be given a referendum," Mr Cameron said. "If you read the Bill it is really clear. This is a manifesto pledge delivered and I am really proud of that."
He added: "We are going to show in this debate that what the Government is proposing does what it says on the tin."
Foreign Secretary William Hague, MP for Richmond, said the new law would be the strongest defence of national democracy in Europe.