On Wednesday, its ally Russian Federation vetoed a U.N. Security Council resolution to condemn the attack.
Damascus and allies in Moscow have denied the regime attacked the village with chemical weapons, maintaining that the casualties were caused by gases released after an al-Qaeda-affiliated ammunitions depot was hit by conventional munitions in a legitimate government air raid.
Syrian president Bashar al Assad has questioned whether last week's alleged chemical weapons attack actually happened, saying there are "a lot of fake videos now".
The chemical attack prompted President Trump to order a missile strike at a Syrian military air base last week.
He said investigators have collected samples that have been sent for analysis.
"What they said was about the desirability, stability and unity of Syria and defeating terrorism".
Syria joined the OPCW in 2013 under severe worldwide pressure following a deadly chemical attack on a Damascus suburb.
The investigation should be carried out "transparently, independently and professionally" both in the airbase where the Syrian aircraft allegedly carrying chemical weapons took off, and in the area where the alleged toxic gas was used, Lavrov said. Rebel groups have also been accused of using chemicals.
A barrage of United States missiles at a Damascus military airport had not diminished his government's ability to carry out strikes.
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The U.S. airstrikes this week were aimed at a Syrian air base, but nearly certainly got the attention of another adversary - North Korea.
An investigation is now being requested by the OPCW.
"There was no order to make any attack, we don't have any chemical weapons, we gave up our arsenal a few years ago", he said.
The Kremlin in a statement confirmed that Putin and Erdogan had spoken "in favor of conducting an objective and full worldwide investigation as soon as possible".
"UK scientists have analysed samples taken from Khan Shaykhun".
According to the report, the official underlined that the us did not know in advance that the attack was going to take place. The organization has not revealed any details, citing the need to preserve the integrity of the probe and the safety of OPCW staff.
Later on Wednesday, the Syrian army said that an airstrike by the USA -led coalition killed "hundreds" in Deir al-Zor province when it hit poison gas supplies belonging to ISIS, releasing a toxic substance. "We think that it is important to defeat terrorists, which in that particular theatre is represented by among others by the ISIS".
The strains in ties were clear as US Secretary of State Rex Tillerson received a frosty reception Wednesday on a visit to Moscow, where he said there was now "a low level of trust" between the two countries.