President Recep Tayyip Erdogan will meet his US counterpart Donald Trump on the sidelines of a G20 summit at the end of June in Japan, the Turkish president’s communications director said.

Erdogan and Trump made the decision during a phone call on Wednesday, Fahrettin Altun said on Twitter.

White House spokesman Judd Deere confirmed the call and said the two leaders discussed a number of bilateral issues, including Trump’s halving of tariffs on steel from Turkey and the country’s planned purchase of the S-400 missile defence system from Russia.

The G20 summit is scheduled for June 28 and 29 in Japan’s Osaka.

The planned meeting comes amid ongoing tension between the NATO allies over Ankara’s purchase of an advanced Russian missile system.

Erdogan has reiterated to Trump his proposal to set up a working group on planned delivery of the Russian S-400 to Turkey, Altun said, adding that the leaders discussed “bilateral and regional issues.”

Erdogan has repeatedly said that Turkey will not backtrack on a deal to acquire Russia’s S-400 surface-to-air missile system despite disapproval and mounting pressure from Washington.

The United States said a NATO ally should not acquire such equipment from an adversary and warned that Turkey risked being ejected from the F-35 fighter jet programme as a result of the deal.