George Osborne has raised the prospect of Britain stopping Turkey from becoming a member of the European Union.
The Government has also made it "absolutely clear" that it would prevent Turks moving to the UK if the country did join the 28 member block with high levels of poverty, the Chancellor said.
It follows an outline deal between the EU and Turkey which will see the state take back migrants who manage to make it across the Aegean to Greece.
In return Ankara is seeking a doubling of EU funding to £4.6 billion - with around £500 million coming from the UK - as well as a relaxation of visa requirements for Turkish nationals and faster progress on accession talks.
But ComRes polling found half the public are opposed to Turkey becoming an EU member.
He told BBC One's Andrew Marr Show: "We have a veto over whether Turkey joins or not. We can set conditions and we have made it absolutely clear that we will not accept new member states to the European Union and give them unfettered free movement of people unless their economies are much closer in size and prosperity to ours.
"We have made absolutely clear that while countries might or might not accede, we would have to make that decision at the time, they would only have free movement of people if the economies were of similar prosperity."
He added: "I don't frankly think Turkish accession is on the cards any time soon. We could, if we wanted to, veto it as other countries could."
Mr Osborne insisted the EU referendum was the biggest decision Britain faced for 50 years.
The country has "control over your destiny by engaging with the world, not running away from it".
Mr Osborne also appeared to take swipe at Brexit campaigner Boris Johnson, who came in for criticism over his performance during a recent appearance on the programme.
"If people want a politician who is just going to sit here and blather away and not actually do anything, then get someone else," he said.
Mr Osborne also dismissed the London mayor's claims that Britain could achieve a Canadian-style trade deal, insisting the agreement took seven years to negotiate and still meant there were tariffs on exports such as cars and beef.
"I hear people saying 'I want Britain to be like Switzerland, I want Britain to be like Norway, I want Britain to be like Canada. You know what, I want Britain to be like Great Britain," he said.
Roland Rudd, treasurer of Britain Stronger in Europe, claimed Mr Johnson had wanted Britain to stay in the EU but changed his mind over the course of a weekend.
The City public relations expert told Pienaar's Politics on 5 Live that it was "absolutely clear he was for in".
"I like him enormously on a person level," Mr Rudd said. "Like a lot of people I have conversations with him, pretty recent, and it was absolutely clear he was for in.
"Absolutely clear. Not any shade of doubt at all."
He added: "Of course he has worries about sovereignty, yes. But he had worries about sovereignty from somebody who was supporting the European Union. He's clearly changed his mind over a weekend."
Former Cabinet minister Owen Paterson warned the issue of Turkish accession is of "real concern" and would "undoubtedly" influence the outcome of the EU referendum.
He told Murnaghan on Sky News: "This is the lurking, huge iceberg under the surface. There is real concern about it."
"I think the Turkish issue is massive and it did come up on the streets yesterday," he added.
"Letting in 77 million people who have a long, 750 mile, border with, sadly, incredibly unstable, it's hard to call them states, Syria and Iraq, because of the instability along the border, I think is obviously something of real concern to many people."