EU plans to make it easier for Turkish nationals to get visas to travel to Europe will not apply to the UK unless it chooses to opt into the scheme, European Commission sources have confirmed.
A summit of EU leaders in Brussels agreed an action plan of assistance for Turkey, in return for Ankara stemming the flow of Syrian refugees into Europe.
Up to two million Syrians are living in refugee camps in Turkey after fleeing fighting in their neighbouring homeland, and the summer saw growing numbers attempting to move on into Europe - often by perilous boat journeys across the Aegean Sea to Greece.
The arrival of hundreds of thousands of migrants has put immense pressure on members of the EU's border-free Schengen area, prompting a desperate search for means of persuading Syrians to stay put.
As well as holding the prospect of an "acceleration" of visa liberalisation and a renewed drive on talks about joining the 28-nation bloc, the new package includes "substantial" EU financial assistance.
The plan puts no figure on the EU funds on offer, but Commission sources said a figure of 500 million euros (£370m) drawn from existing budgets, was discussed in the meeting, which lasted into the early hours.
It is understood that visas would initially be made more freely available only to business people, in order to build trust, before being gradually extended to other classes of traveller.
The visas would be valid only in the Schengen area, exempting non-members Britain and Ireland - unless they chose to opt in.
Speaking after the conclusion of the one-day summit European Council president Donald Tusk voiced "cautious optimism" about the plan, which he described as a "major step" towards reducing numbers of Syrian refugees reaching Europe.
But he said any liberalisation would depend on "a responsible and adequate response from the Turkish side" in terms of reducing numbers of migrants.
"An agreement with Turkey makes sense only if it effectively contains the flow of refugees," said Mr Tusk.
But Ukip leader Nigel Farage denounced the plan. "This Commission proposal is bordering on insanity," said Mr Farage. "Agreeing to liberalise border requirements for 75 million Turkish nationals is a form of EU madness.
"From a cost, security and cultural perspective, this is completely the wrong move. If Cameron and Co allow this to happen it's the British people who will be the turkeys at Christmas. Yet another reason to leave the EU."
European Commission president Jean-Claude Juncker stressed that any moves towards visa liberalisation would not mean free entry into the EU for all Turks.
Mr Juncker said: "We have agreed with our Turkish partners that the visa liberalisation process will be accelerated. This does not mean that we would step away from the basic criteria, which are the rules in that domain. There will be no other criteria for Turkey and we will assess progress in spring 2016.
"We are establishing a link between the delivery of Turkey as far as migration is concerned and the visa issues."