BRUSSELS • Prospects for a grand bargain between Europe and Turkey to stem a flow of migrants into the continent are uncertain days before a summit on Sunday meant to seal a deal and put fraying relations back on a firm footing, EU and Turkish officials say.

How much money Turkey will receive for settling more Syrian migrants, the pace at which Turkey's long-stalled EU membership bid can be accelerated and whether Brussels can deliver on its promise of easier travel for Turks are all unresolved.

"We are not there yet," said a senior European Union official.

Turkish officials also said they had not finalised an agreement, raising questions about whether Ankara was holding out for a better deal at the summit.

Officials want it to be essentially a signing ceremony, attended by the EU's 28 leaders. Turkish President Tayyip Erdogan will not be attending, despite his desire for more high-level contact with EU leaders. He will leave the meeting in Brussels to Prime Minister Ahmet Davutoglu.

European Commissioner Johannes Hahn, who handles EU enlargement policy, told Reuters last week the summit would mark a "fresh start" with Turkey a decade after Ankara started its membership talks to join the European Union.

The EU wants to see Turkey help curb the influx into Europe of migrants, including refugees from Syria's civil war, in return for €3 billion (S$4.5 billion) in EU aid over two years. While €500 million comes from the EU's budget, the remainder must be raised from EU governments. Most have not said how much they will offer, leaving it unclear if the fund can indeed reach €3 billion.

Turkey is seeking €3 billion a year, according to a senior EU official involved in negotiations with Ankara.

European Council President Donald Tusk, the former Polish prime minister who now chairs EU summits, called the summit earlier this week in an apparent move to force Turkey's hand.

Central to the success of any EU-Turkey deal is the end of the stalemate on Cyprus, the Mediterranean island divided for four decades between the Turkish-controlled north and Greek Cypriot south, which joined the EU in 2004. "The Turkish are now playing a constructive role in Cyprus, but we have an interest not to overload the boat," said a senior EU official. "Turkey's membership talks have to run in parallel with the Cyprus talks."

One risk is that Turkey may push too hard to open new negotiations with the EU. Six new so-called "chapters" of talks, including energy, the judiciary and security, may be opened by spring, but all 28 EU states must agree to it.

Differences between the EU and Turkey may also arise on the issue of visa-free access to the EU for Turkish citizens. A deal would entail full visa liberalisation from 2017, but only after Ankara implements the migration deal for at least six months.

But the new security threats in Europe exposed by the deadly ISIS attacks on Paris may harden some EU states against opening up borders to a large Muslim population.

Meanwhile, the Canadian government on Tuesday pushed back to the end of February its deadline for accepting 25,000 Syrian refugees, in a concession that its original Jan 1 target was too difficult to meet.

Liberal Prime Minister Justin Trudeau, sworn in this month, made the initial pledge part of his election campaign, but a wide array of critics said the goal was unrealistic.

"We just looked at the logistics, we looked at what it would take to bring them in by Jan 1, and we had options around that," Mr Trudeau told the Canadian Broadcasting Corp. "We realised that we wanted to make sure that it was done absolutely right."

The government will fly in 10,000 refugees by the end of the year and the remainder by end-February.

REUTERS