VARNA, Bulgaria - President Recep Tayyip Erdogan on Monday insisted Turkey still wanted to become a member of the European Union ahead of a potentially stormy summit with EU chiefs seeking to repair an increasingly fractured relationship.

European Union President Donald Tusk and European Commission chief Jean-Claude Juncker will talk with Erdogan at the Bulgarian Black Sea resort of Varna with a litany of problems clouding their discussions.

Topic expected to be high on the agenda include the crackdown in Turkey after July 2016's failed coup, Ankara's demands for visa liberalisation and the near-endless saga of the country's own EU membership bid.

And a row over Greece and Cyprus that erupted last week has added another point of contention just days before the talks.

Before departing Istanbul for Bulgaria, Erdogan said Turkey was still seeking to become a full EU member and blasted the bloc for what he said were "double standards" towards Ankara.

"EU membership continues to be our strategic target," Erdogan said. But Erdogan added: "We are going to remind them (Tusk and Juncker) once more that Turkey will not tolerate hypocrisy."

Bulgarian Prime Minister Boyko Borisov, whose country holds the rotating presidency of the EU Council, said it was expected to be "a very difficult meeting".

Juncker said he was "looking with mixed feelings towards the summit because the differences in views between the EU and Turkey are many".

But he added that "we will have a frank and open debate with President Erdogan".

Temperatures were raised last week after EU leaders condemned Turkey's "illegal actions" towards Greece and Cyprus in the eastern Mediterranean and the Aegean Sea. Ankara hit back at the "unacceptable comments" and said the EU had lost its objectivity on Cyprus, which is divided between the Greek-majority internationally recognised Republic of Cyprus and the breakaway Turkish Cypriot north.

The statement on Thursday by the 28 EU members meeting in Brussels condemned Turkey over Ankara's arrest of two Greek soldiers and its promise to prevent the Greek Cypriot government from exploring for oil and gas.

Ankara and Brussels had in March 2016 agreed a controversial deal to stop the flow of migrants, in what was seen as a landmark in cooperation and which Turkey hoped would yield visa free travel to Europe.

So far this incentive has not been realised and Erdogan is expected to press this point strongly in the talks.

Brussels has repeatedly criticised the post-coup crackdown, which has seen nearly 160,000 people detained, including dozens of journalists.

Turkey, for its part, has accused Brussels of failing to show solidarity after the coup and appears set on forging a strong partnership with President Vladimir Putin's Russia.

In contrast to Erdgogan's brisk evening meeting with the EU leadership, Putin is expected to make a full two-day visit to Turkey next week.

Ankara has agreed to buy air defence systems from Russia and Moscow will also build Turkey's first nuclear power station.

In his comments before leaving Istanbul, Erdogan lashed out at "some circles whose intentions and goals we know inside and out" who wanted to block Turkey from becoming a full EU member.

Next month the EU will release its latest progress report, which is "bound to illustrate a substantial regression" in Turkey, Marc Pierini, a visiting scholar at Carnegie Europe and a former EU ambassador to Turkey, said in a study.

During a visit by Erdogan to Paris earlier this year, French President Emmanuel Macron said Ankara should settle instead for a looser "partnership" and suggested no more progress was possible in accession talks.

Analysts were sceptical that given the current tensions there would be any breakthrough at the Bulgarian resort.

"The Varna summit will provide a platform to re-launch the dialogue between the two parties, even though no real breakthrough is expected in concrete terms," said Jana Jabbour, professor of political science at Sciences Po university in Paris and the author of a book on Turkish foreign policy.