The in/out referendum on Britain's membership of the European Union could be held as soon as next year, Philip Hammond has confirmed.
The foreign secretary also accused Labour of having been "blind, deaf and dumb" to the public's desire for changes to be made to the EU.
David Cameron has been touring European capitals in an attempt to renegotiate the UK's membership of the EU. That new deal will be put to the public in a referendum by the end of 2017. Cameron is expected to recommend an 'in' vote.
However Hammond told the House of Commons on Tuesday that the vote could be held sooner. "We don’t intend to wait until the end of 2017," he said. The foreign secretary said the vote would be held "as soon as we are ready".
He told MPs if other EU leaders embraced Britain's proposals for a looser relationship with Brussels "with enthusiasm" then "we may be able to get to a position where a referendum in 2016 is possible".
Earlier today, Boris Johnson said cabinet ministers should be allowed to campaign to leave the EU without quitting the government.
His comments put pressure on Cameron, who yesterday appeared to perform a sharp U-turn on the issue. Having initially seemingly said ministers would have to quit to campaign on the opposite side of the referendum campaign, he then said his mind was not made up.
The prime minister's official spokesperson said of Boris' comments: "The prime minister is clear he thinks the approach during the the referendum is an issue for further down the road. We need to take this step by step. Of course people are going to express views. There are going to be a lot of views during the re negotiation."
Hammond insisted today that Cameron had been "consistent" in his position and had been "misinterpreted" by reporters. He told MPs it was "simply hypothetical to talk about who will be allowed to do what" in the campaign as the outcome of the renegotiation was not yet known.
Boris told LBC radio: "I think in 1975 from memory I think cabinet ministers were allowed to campaign against staying in and to keep their positions. I don’t see why not myself.
"Just thinking about it out loud on the spur of the moment let me think: I think probably it would be safer and more harmonious just to say 'OK you make your minds up'.
"I think probably on something like this, do you really need to bind everybody in? There will be different views, get it over.
Boris added: "The prime minister will be able to make a recommendation. It’s almost certain if he gets the deal that he wants the overwhelming majority of his colleagues on both the front and backbenches will support him."
Asked if he would join the 'out' campaign, Hammond told the Commons that like the prime minister he "rules nothing out".