It would pave the way for an in-out vote by the end of 2017 that will decide Britain's geopolitical and economic destiny for decades ahead.
Cameron's highly unusual decision to sanction the draft bill was announced in the US on Monday.
"There's not going to be a referendum tomorrow," said Cameron.
"Is it in our interests to reform the European Union to make it more open, more competitive, more flexible, and to improve Britain's place within the European Union? Yes, it is in our national interests. And it's not only in our national interest, it is achievable, because Europe has to change," he continued.
Conservative critics have been pressing Cameron to b
ring forward the referendum to before the next national election in 2015 - or to commit to it being held before the end of 2017. The public debate has made his party look divided.
It will be hard for the Conservatives to push any referendum bill through parliament because it will almost certainly be opposed by their pro-EU coalition partners, the Liberal Democrats, as well as the opposition Labour Party.
Source: Euronews
