Foreign Minister Mevlüt Çavuşoğlu and his U.S. counterpart Mike Pompeo met in Singapore on Friday in a "constructive" meeting, according to a diplomatic source.

The meeting was held on the sidelines of the Association of Southeast Asian Nations (ASEAN) foreign ministers' meeting, the source, who asked not to be named due to restrictions on speaking to the media.

Çavuşoğlu, in comments to Turkish broadcasters, said the United States and Turkey had agreed to work closely to resolve issues between them.

Their talks came after Washington imposed sanctions on two Turkish ministers over the trial of a U.S. pastor accused of backing terrorism. Turkey has called the U.S.' threats and sanctions unacceptable.

The Turkish foreign minister also said he and Pompeo discussed potential joint steps the two countries could take regarding Syria's Idlib and Manbij. The NATO allies have also been at odds over Syria policy.

The two top diplomats frequently talk over the phone; last time that happened was on Wednesday upon the request of the U.S. side, which marked the fourth such conversation over the last 15 days.

Earlier, Çavuşoğlu also met Indonesian, Japanese and Iranian counterparts separately at ASEAN.