Turkish President Recep Tayyip Erdogan has threatened to scrap a deal with the European Union to readmit migrants who have crossed illegally into Europe.
It comes amid a stand-off with European nations over their reluctance to allow Turkish ministers to hold campaign rallies in their countries.
In a televised speech, Mr Erdogan said the EU could “forget about” a migrant deal first struck in 2013 and revived last year.
Turkey had agreed to work to keep migrants from crossing into the EU in return for funds to help it deal with some three million refugees.
Mr Erdogan accused the EU of not sticking with a promise to grant Turkish nationals the right to travel visa-free in Europe. He also sharply criticised a European court ruling in favour of curbs on wearing Islamic headscarves.