Turkish Foreign Minister Mevlut Cavusoglu and US Secretary of State Rex Tillerson on Wednesday discussed the issue of mutual visa suspension via phone, Turkey’s state-run Anadolu Agency reported.

Tillerson expressed his “profound concern” over the detention of staff at US diplomatic missions in Turkey during his talks with the Turkish foreign minister, according to a statement by the US State Department. He also called on the Turkish government to present evidence behind the accusations against two locally employed staff who were arrested in Turkey this year.

The detentions prompted Washington to stop issuing visas and triggered a diplomatic crisis.

The building of the Consulate General of US in the Istinye district of Istanbul /Anadolu Agency Photo

The phone call marks the first time the two top diplomats spoke since the visa crisis broke out last Sunday.

Earlier the same day, Turkish Prime Minister Binali Yildirim expressed hopes to normalize the strained Turkey-US relationship as soon as possible.

The strained relations between the two NATO allies escalated last week after Turkey arrested a Turkish employee of the US consulate on suspicion of links to US-based Muslim cleric Fethullah Gulen, who is accused by Ankara of being behind a failed coup attempt in July 2016.

The US Embassy in Ankara on Oct. 8 announced it had suspended non-immigrant visa services at all diplomatic facilities in Turkey. In response, Turkey’s Washington Embassy also suspended non-immigrant visa services in the US, citing security concerns.