Turkish President Recep Tayyip Erdogan on Thursday warned the European Union that Ankara would not implement a key deal on reducing the flow of migrants if Brussels failed to fulfil its side of the bargain.
Erdogan's typically combative comments indicated that Ankara would not sit still if the EU fell short on a number of promises in the deal, including visa-free travel to Europe for Turks by this summer.
"There are precise conditions. If the European Union does not take the necessary steps, then Turkey will not implement the agreement," Erdogan said in a speech at his presidential palace in Ankara.
"Everything that has been promised (must be put into action by the EU), everything that is specified under the accord."
The March 18 accord sets out measures for reducing Europe's worst migration crisis since World War II, including stepped-up checks by Turkey and the shipping back to Turkish territory of migrants who arrive in Greece.
In return, Turkey is slated to receive benefits including visa-free travel for its citizens to Europe, which in the accord is promised "at the latest" by June 2016.
Turkey is also to receive a total of six billion euros in financial aid up to the end of 2018 for the 2.7 million Syrian refugees it is hosting.
Meanwhile, its long-stalled accession process to join the EU is to be re-energised.
"Some three million people are being fed on our budget," said Erdogan, referring to the Syrian refugees on whose welfare Turkey says it has spent some $10 billion since the Syrian conflict began in 2011.
"There have been promises but nothing has come for the moment," said Erdogan.
"We have received lots of thanks for our action on the refugees and in the fight against terrorism. But we are not doing this for thanks."
"Everything should happen in line with what has been promised, what has been set out in the text," he added.
The first transfer of over 200 migrants from the Greek islands of Lesbos and Chios to Turkey took place on Monday. But the process has been stalled by a last-minute flurry of asylum applications by migrants desperate to avoid expulsion.
Since then, there have been no more transfers.
Nikos Xydakis, Greece's junior foreign minister for European affairs, said it would take "at least two weeks" to process the first batch of asylum applications.
Under the pact with the European Union, Turkey has agreed to take back migrants who arrived in Greece in illegal crossings of the Aegean Sea after March 20.
It also agreed to allow one Syrian refugee to travel to Europe in exchange for every one that it takes back on its soil.
The deal has caused huge controversy, with rights groups including Amnesty International claiming Turkey could not be considered a "safe country" for the return of refugees.
Pope Francis will meanwhile visit the Greek island of Lesbos on April 16 to show his support for the migrants, many of whom have protested at the prospect of being deported to Turkey.