A deal to grant Turks visa-free travel to most of the European Union was hanging by a thread after President Recep Tayyip Erdogan defiantly vowed Ankara would not fulfil a key condition set by Brussels.
With alarm growing over the deal's future, European Commission chief Jean-Claude Juncker bluntly told Erdogan that Turks would only enjoy travel to the passport-free Schengen area if all conditions were met and it would be "his problem" if this failed to materialise.
The promise of visa-free travel is a key pillar of the landmark March accord for Turkey to stem the flow of migrants to the EU and this could now also be in peril.
Erdogan accused the European Union of "hypocrisy" for telling Ankara to adapt its counter-terror laws in return for visa-free travel while it was in the throes of fighting Kurdistan Workers' Party (PKK) rebels.
"The EU stands up and says 'soften your approach over the terrorist organisation'," Erdogan said in a speech in Ankara, referring to the PKK.
"Since when are you running this country? Who has given you the authority?" he asked, in one of his most stinging attacks in recent weeks on the EU.
"They believe they have a right for themselves (to fight terror) but find it a luxury and unacceptable for us. Let me say it clearly -- this is called hypocrisy."
Explosion shakes southeast
Turkey concluded a deal with the EU in March to curb the migrant flow to Europe in return for political incentives including the visa-free travel as well as billions of euros in aid from Brussels for refugees.
Ankara however is obliged to meet the remaining five out of 72 conditions for its citizens to enjoy visa-free travel to Europe.
But with the Turkish military battling the PKK in the Kurdish-majority southeast, Turkey says it cannot change its counter-terror laws.
On Thursday, a blast hit the southeastern majority Kurdish city of Diyarbakir, killing four "bombmakers" and wounding at least 10 other people, according to the country's interior ministry.
The explosion came hours after at least eight people including soldiers were injured by a remotely detonated car bomb aimed at a military vehicle in Istanbul, according to the local governor's office.
- 'Not my problem, his problem' -
Speaking in Berlin, Juncker indicated the EU saw no room for negotiation if Turkey did not fulfil all the conditions.
"We consider that it is important for these conditions to be fulfilled, otherwise this deal between the EU and Turkey will not happen," Juncker said.
"If Mr Erdogan wants to pursue his strategy, then he has to answer to the Turkish people why Europe is denying free travel to Turks. That's not my problem, that will be his problem."
The EU wants Ankara to sharply narrow its definition of "terror" to prevent recent cases like the prosecution of academics and journalists for publishing "terror propaganda".
A European diplomat told AFP: "We don't have a plan B" if the deal -- which so far helped migrant flows to Europe fall sharply -- collapses.
German Chancellor Angela Merkel, who spearheaded efforts to conclude the deal, said, "We must recognise that we need such an agreement with Turkey in any case and that it is worth the effort to negotiate it even if difficulties arise".
The Turkish minister of European affairs, Volkan Bozkir was set to meet Johannes Hahn, the commissioner for European enlargement negotiations, in Brussels on Friday morning.
Turkey has for decades sought to become a member of the EU but its bid has hit repeated stumbling blocks, sparking increasing bitterness in Ankara.
Erdogan, who has sought to build closer relations with key Arab and Asian states during his presidency, said Turkey had alternatives to the EU.
"In the period ahead of us, either we will develop our relations with the EU and finally get on this road or we will find a new road for ourselves," he said.
"We prefer to build a new Turkey together with our European friends. We will now await our European friends' decision."