"The use of chemical weapons is inadmissible. This does not mean, however, that one can usurp the right to accuse and pass verdicts," Lavrov told the UN General Assembly.

The United States, Britain and France have accused Assad's army of carrying out an August 21 chemical weapons attack near Damascus. But Russia has sided with Assad in blaming the foreign backed militant groups.

The United States and Russia have agreed a resolution, to be voted by the UN Security Council on Friday, on destroying Syria's chemical weapons. But Lavrov's comments signaled no major change in Russia's defense of its Syrian ally.

Lavrov told the assembly: "All the incidents associated with the use of chemical weapons by whoever that might be in Syria must be investigated in a professional and unbiased manner."

He added that the accusations should "then be examined by the UN Security Council exclusively on the basis of facts rather than allegations and assumptions."

Lavrov said it was "alarming" to hear world leaders talk about "the right to use military force to ensure one's own interests in the Middle East region."

The Russian minister did not mention the United States, but US President Barack Obama on Tuesday said he was ready to order military force in the Middle to defend US "core interests".

NJF/NJF