German Chancellor Angela Merkel has said she will not shy away from controversial issues when she meets Turkish president Recep Tayyip Erdogan later, amid criticism the German leader has made too many concessions to save the EU-Turkey migration deal.

Ahead of a two-day trip to Istanbul to attend a UN refugee summit with 50 other representatives and heads of state, Merkel rejected accusations in an interview with Frankfurter Allgemeine Zeitung newspaper that the EU has become too dependent on Turkey because of the migration deal.

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“Of course there are mutual dependencies, which you could also call a necessity to reconcile interests,” Merkel said.

Merkel has championed the deal that allows Greece to send back migrants to Turkey, despite concerns over Turkey's rights record and treatment of refugees.

Erdogan has used the deal to shore up his power at home, and used it as a bargaining chip with Europe. He has threatened to scrap the deal if Turkey does not get visa liberalisation from the EU.

On her fifth visit to Turkey in eight months, Merkel is trying to strike a balance between protecting the deal and avoiding being seen as accommodating too much to Erdogan’s whims.

In the Frankfurter Allgemeine Zeitung interview, the German chancellor criticised the Turkish parliament’s vote on Friday to deprive almost all of the MPs from the main pro-Kurdish of their legal immunity.

The move paves the way for Turkey to put many of its leading Kurdish politicians on trial.

“We want that the Kurdish people have their equal place and a good future in Turkey,” Merkel said, adding she would raise “all the important questions” with Erdogan.

She also criticised the breakdown of talks between the government and the Kurdish community last year.

Pushing Turkey's membership bid

Merkel also remains under pressure at home because of the deal.

She was criticised last month for allowing the prosecution of a German comedian who made fun of Erdogan after a complaint from the Turkish leader.

Horst Seehofer, leader of the CSU, the sister party to Merkel’s Christian Democrats, said Sunday that the pact had “mixed up things that have nothing to do with each other” by linking the refugee issue with Turkey’s bid to join the EU and visa-free travel.

“One should never allow oneself to be blackmailed,” Seehofer said.

In the interview, Merkel stood by the deal, saying: “I am convinced that it’s in German, European and Turkish interests, and especially in the interests of those who are fleeing war and persecution.”

She added she is irritated by what seems like some people almost looking forward to the deal failing.

The visit comes as one of Erdogan’s closest allies, Binali Yildirim, was officialy appointed prime minister on Sunday after he was elected chairman of the ruling Justice and Development party (AKP).

In his first speech Yildirim said the time has come for the EU to be clear about Turkey’s membership process.

“The time has come to know what they think about Turkey,” he said.