Russia's foreign minister says the evidence put forth by the United States of chemical weapons use in Syria apparently doesn't meet stringent criteria for reliability.

The Obama administration said this week that it will give lethal aid to Syrian rebels in light of evidence that President Bashar Assad's forces used chemical weapons in the country's civil war.

In Moscow, Foreign Minister Sergey Lavrov said Saturday that the material does not include guarantees that it meets the requirements of the Organization for the Prohibition of Chemical Weapons.

He said the organization specifies that samples taken from blood, urine and clothing can be considered reliable evidence only if supervised by organization experts from the time they are taken up to delivery to a laboratory.