The UN Secretary-General Ban Ki-Moon has expressed concern about a draft deal between the European Union and Turkey aimed at resolving the migrant crisis.

Under the plans refugees who reach Greece would be sent back to Turkey.

The UN's refugee agency says that is illegal under international law.

Ban Ki-Moon says he is "deeply worried by growing anti-migrant and anti-refugee rhetoric".

"I am deeply concerned about any arrangement that would involve the blanket return of anyone from one country to another without spelling out the refugee protection safeguards," UN High Commissioner for Refugees Filippo Grandi said.

Meanwhile, Sinn Féin MEP Liadh Ni Riada says the the European Union simply doesn't have enough money to cope with issues like the refugee crisis:

"I have been jumping up and down about this for quite a long time calling for a revision of the multi-annual financial framework," she said.

"We basically don’t have enough money in the European budget to deal with all the crises that are happening.

"For instance the refugee crisis, they have created an additional fund outside the budget capacity - How is that going to be funded? These are practical issues that need to be addressed," she added.

There was a potential breakthrough in talks between EU leaders and Turkey overnight, aimed at reducing the number of migrants coming to Europe.

Turkey says it will take back people who make the crossing to Greece, if an equal number of Syrian refugees from its country are settled elsewhere.

Turkey also wants more aid money and to talk about its future membership of the EU.

After 11 hours of talks, which included Turkish Prime Minister Ahmet Davatoglu, EU leaders laid out a plan which will aim to tackle the numbers of refugees leaving Turkey for Greece - as well as control illegal smugglers profiting from the dangerous journeys taken by refugees across the Aegean Sea.

Among other things on the horizon - for every illegal migrant found crossing to Turkey - the EU has agreed to return them to Turkey and in exchange will relocate another refugee inside an EU member state.

In addition, Turkey is to receive around €6 billion to invest in refugee welfare.

European Council president Donald Tusk is welcoming the idea:

"This operation wouldn't work without Turkey's readiness to take back all irregular migrants who have been apprehended on Turkish waters.

The days of irregular migration to Europe are over."

Turkey's prime minister Ahmet Davutoglu said:

"Our objective is to discourage illegal migration, to prevent human smugglers.

"Our main objective is humanitarian. We don't want to see women and children dying in the Aegean Sea."