Turkish President Recep Tayyip Erdogan has threatened to tear up a key migrant deal with the European Union.
He said the EU could "forget about" Turkey re-admitting failed asylum seekers who had reached Europe via Turkey, a key part of the agreement.
Mr Erdogan also said the EU's top court was leading a "crusade" against Islam.
His comments are the latest in a widening, increasingly acrimonious dispute with EU governments and institutions.
The Turkish government has been enraged by Germany, the Netherlands and other nations' decisions to block its officials from holding political rallies in those countries.
It wants to win the votes of large Turkish populations living in Europe ahead of a key referendum that would expand Mr Erdogan's executive powers.
The EU has criticised the referendum, saying it would concentrate too much power in the president's hands.
The migrant deal, signed in March 2016, saw Turkey promised aid, visa-free travel for its nationals and accelerated EU membership talks in return for its help in reducing the flow of migrants crossing to Europe.
The number of migrants reaching Greece by sea dropped sharply after the deal was reached, and Turkey's continued co-operation with the EU is regarded as crucial in managing the mass arrival of migrants fleeing war and poverty in Africa and the Middle East.
President Erdogan said the EU had broken its promise of granting visa-free travel to Turks.
"Now they say readmission. What readmission? Forget about it," he said.
"You don't let my minister into the Netherlands. You revoke the landing rights of my foreign minister. You prevent [us] holding meetings at the General Consulate building, which is my land. But after that you'd expect us to do this [re-admit migrants]. That's not going to happen."
On Wednesday Turkish Foreign Minister Mevlut Cavusoglu said Turkey could immediately stop implementing the agreement if it wanted to, echoing previous threats made by the Turkish government
The EU Commission has said that it expects Turkey to comply with its commitments under the accord.
More than 1.2m first-time asylum seekers sought protection in the EU last year, Eurostat has announced, with Syrians, Afghans and Iraqis making up the largest groups.
Although the numbers were slightly less than in 2015, they were more than double that who applied in 2014. Six in every 10 applied in Germany.
Turkey hosts more than three million refugees, making it the country with the largest refugee population, according to the European Commission.
Mr Erdogan's latest remarks follow a series of inflammatory comments about Germany and the Netherlands, including accusing them of Nazi-like behaviour for banning rallies.
German Chancellor Angela Merkel and French President Francois Hollande on Thursday said such remarks were "unacceptable".
But the Turkish leader is showing no signs of toning down his rhetoric. He has also denounced a European Court of Justice verdict permitting private companies to ban workers from wearing religious symbols in the workplace under certain conditions.
"They started a clash between the cross and the crescent, there is no other explanation," he said.
Turkey is furious at a decision taken by the Netherlands on Saturday to bar two Turkish ministers from addressing expatriates in the country, citing "risks to public order and security".
Some 5.5 million Turks live outside the country, including an estimated 400,000 in the Netherlands.
In retaliation, Turkey barred the Dutch ambassador from returning to Ankara, and suspended high-level relations with The Hague in a raft of diplomatic sanctions.
Dutch Prime Minister Mark Rutte's party won Wednesday's election in the Netherlands. Mr Erdogan responded by saying that although he had won the election, he had lost Turkey's friendship.