Russian Foreign Minister Sergei Lavrov and US Secretary of State Rex Tillerson discussed the Syrian settlement during a phone conversation, media reports said.

The diplomats on Friday exchanged views on the tasks of de-escalating tensions, giving stability to the ceasefire regime, increasing anti-terror efforts, and intensifying external assistance to the intra-Syrian negotiation process, said a Russian Foreign Ministry statement.

Lavrov and Tillerson also touched upon regional and bilateral issues and agreed on further Russia-US contacts, Xinhua news agency reported.

"The secretary looks forward to further meetings with the foreign minister to discuss the respective roles of the United States and Russia in de-escalating the conflict and supporting the talks in Geneva to move the political solution forward," the statement added.

Friday's conversation came three days after Russian President Vladimir Putin and US President Donald Trump agreed to intensify the dialogue between Lavrov and Tillerson on the search for options that help consolidate the truce among conflicting factions within Syria.

In a latest move toward a political settlement of the chronic civil war, Russia, Iran and Turkey signed a memorandum on Thursday in the Kazakh capital of Astana on the creation of four de-escalation zones in Syria.

Also on Friday, the Russian General Staff said that Russia has stopped operations of its military aircraft since May 1 in regions where the de-escalation zones will be officially established on Saturday.