U.S. Secretary of State Rex Tillerson (L) and Russian Foreign Minister Sergei Lavrov attend a joint press conference in Moscow, Russia, on April 12, 2017. (Xinhua/Bai Xueqi)

MOSCOW, April 21 (Xinhua) -- Russia and the United States agreed on Friday to study the feasibility of organizing an objective inquiry into a chemical incident in Syria's Idlib Province, the Russian Foreign Ministry said.

Russian Foreign Minister Sergei Lavrov and U.S. Secretary of State Rex Tillerson discussed the issue in a phone conversation, the ministry said in a statement.

In the phone talk, Lavrov expressed regret that Washington opposed Russia's initiative at the Organization for the Prohibition of Chemical Weapons (OPCW) of sending inspectors to Syria to verify allegations of the use of sarin gas and of the presence of poisonous substances at the Syrian airbase Shayrat, the statement said.

"The interlocutors agreed to give instructions to study once again the possibility of an objective investigation of the incident under the auspices of the OPCW," the statement read.

The OPCW convened on Thursday to vote on the proposal put forward by Russia and Iran on the immediate beginning of a full investigation into the Apil 4 chemical attack.

According to the British delegation to the OPCW, the organization's executive council has "overwhelmingly rejected" the proposal.

While discussing issues on the bilateral agenda, Lavrov and Tillerson also agreed on the early start of the joint working group at the level of deputy foreign ministers in search for ways to remove irritants from bilateral relations, the statement said.