Russian Foreign Minister Sergei Lavrov in a telephone conversation with his US counterpart, Rex Tillerson, expressed a regret over Washington's opposition to the Russian-Iranian proposal to investigate the alleged chemical attack in Syria in early April.

The United States initiated the conversation

"A telephone conversation between Russian Foreign Minister Sergey Lavrov and US Secretary of State Rex Tillerson was held on the US initiative," the Russian Foreign Ministry said.

During the conversation, Lavrov "regretted The United States opposition to the International Organization for the Prohibition of chemical weapons (OPCW) initiative to send inspectors to investigate information on the use of sarin in Khan Cheikhoun" in Syria on April 4, according to the statement.

Lavrov and Tillerson "agreed to re-investigate the possibility of launching an objective investigation into the incident that would be under the patronage of the OPCW."

Bilateral relations are at the lowest level

They agreed that "a task force in charge of the solutions will resolve disputed issues in bilateral relations as soon as possible." Bilateral relations are at their lowest level after the Cold War, mainly due to the Ukrainian crisis and the conflict in Syria, the statement said.

The State Department noted in a statement that Lavrov and Tillerson mentioned in the conversation the continuation of talks on bilateral issues, and launching the "OPCW investigation to determine if Syria used chemical weapons on April 4".

Tillerson has "reiterated that he supports the mechanism of the current investigation run by OPCW," it is said in a statement without further details.

Russian proposal was rejected this Tuesday

This Tuesday, the International Bureau of Chemical Weapons Ban rejected a proposal by Moscow and Tehran to send a new team in charge of an alleged chemical attack in Syria in early April.

The draft of Russian-Iran proposal is calling for an investigation to "determine whether chemical weapons were used and how were they delivered to the scene of attack".

Both Moscow and Tehran demanded that investigators go to the Shayrat base, which was attacked by the United States, to check the allegations of chemical weapons stocks at that location.

Meanwhile, there is an increasing number of NATO airplanes crossing over Russian military aircraft in the wake of the rising tension between US-Russia relations.