Details on the financing have been holding up the project.

The biggest contributor is Germany, on €427.5 million. The UK gives €327.6 million. France contributes €309.2 million.

Cyprus (split in two after Turkey invaded north Cyprus in 1974) will not contribute. But it will pay € 2.3 million into EU aid for Jordan and Lebanon refugee facilities.

Italy was the last country to agree on the Turkey fund.

It did so after the commission made clear the contributions will not be taken into account for the calculation of a member state's deficit under EU fiscal rules.

The Italian contribution is €224.9 million.

"Turkey now hosts one of the world's largest refugee communities and has committed to significantly reducing the numbers of migrants crossing into the EU," Johannes Hahn, EU neighbourhod commissioner said.

Commission vice-president Frans Timmermans said: "The money we are putting on the table will directly benefit Syrian refugees in Turkey, helping to improve their access to education and healthcare in particular.”

Brussels and EU countries hope that better conditions in Turkish camps will mean fewer people risk the perilous sea crossing from Turkey to Greek islands.

Germany has the biggest stake because most people want to claim asylum there.

The commission originally proposed to contribute €500 million to the Turkey facility.

But member states, in December, talked it up to €1 billion.

The other €2 billion will be paid by member states according to the size of their economies, as with their normal EU budget contributions.

Wednesday's agreement makes it possible for the commission to start providing assistance from early 2016.

The money is being earmarked specificically for refugee camps and doesn’t amount to direct budgetary support for Turkey.