The visit comes at the request of President Recep Tayyip Erdogan and  the two leaders will also discuss steps for further developing cooperation between the two countries, Turkey's Communications Directorate earlier said in a statement.

The statement said Turkey-EU relations, as well as the process of Turkey’s accession to the EU and talks on updating the Customs Union trade deal along with the visa liberalization dialogue be on the agenda in the framework of Germany's EU presidency term, which is set to begin in July.

The two leaders are also expected to exchange views on regional and international issues, particularly Libya and Syria.

Merkel and Erdogan are also set to attend the official opening ceremony for the new campus of the Turkish-German University in Istanbul.

Turkey's accession to EU

Turkey applied for EU membership in 1987 and accession talks began in 2005. 

But negotiations stalled in 2007 due to objections of the Greek Cypriot administration on the divided island of Cyprus as well as opposition from Germany and France.

In 2016, Turkey and the EU signed a deal to stem the irregular migration flow through the Aegean Sea by taking stricter measures against human traffickers and improving conditions for nearly 3 million Syrian refugees in Turkey.

The deal allows for the acceleration of Turkey’s EU membership bid and visa-free travel for Turkish nationals within the Schengen area, on the condition that Ankara meets all 72 requirements set by the EU.

Turkey has long complained of the EU slow delivery of promised funds for refugees and failing to uphold its end of the deal concerning visa-free travel.