In a Saturday statement, Lavrov said the materials collected by the Obama administration regarding the use of chemical weapons by Syrian troops would not meet the requirements of the Hague-based Organization for the Prohibition of Chemical Weapons (OPCW).

On June 13, US Deputy National Security Adviser Ben Rhodes claimed in a White House statement that the Syrian government “has used chemical weapons, including the nerve agent sarin, on a small scale” against the foreign-backed Takfiri militants “multiple times in the last year.”

Syria strongly rejects such claims and says the militants have used chemical weapons on several occasions, including an attack in the region of Khan al-Assal in the northwestern province of Aleppo on March 19, where over two dozen people died.

Lavrov went on to say that only blood, urine and clothing samples taken under direct supervision of OPCW experts can be considered as reliable evidence.

“Blood samples, urine, soil, and clothing are considered serious evidence only in the case where these samples are taken by experts from the Organization for the Prohibition of Chemical Weapons, and if these experts controlled these samples during the entire duration of the investigation in appropriate laboratories,” Lavrov said.

The turmoil in Syria erupted in March 2011, and many people, including large numbers of Syrian soldiers and security personnel, have been killed so far.

UN High Commissioner for Human Rights Navi Pillay said on June 13 that at least 93,000 people have been killed since the outbreak of the foreign-sponsored militancy against the Syrian government.