Russian Foreign Minister Sergei Lavrov accused the United States on Wednesday of supplying weapons to Syria’s rebels.

Russian Foreign Minister Sergei Lavrov accused the United States on Wednesday of supplying weapons to Syria's rebels, which is worsening the conflict engulfing Moscow's allied regime in Damascus, AFP reported.

Lavrov's accusation followed a charge by US Secretary of State Hillary Clinton that she had information Russia was sending to Syria "attack helicopters ... which will escalate the conflict quite dramatically."

Lavrov told a news conference during a brief visit to Iran that Russia was supplying "anti-air defence systems" to Damascus in a deal that "in no way violates international laws."

"That contrasts with what the United States is doing with the opposition, which is providing arms to the Syrian opposition which are being used against the Syrian government," he said, in remarks translated from Russian into Farsi by an official interpreter.

It was the first time Moscow has directly pointed the finger at Washington. Previously, it had said unidentified "foreign powers" were arming the opposition.

Asked in Tehran about the helicopter allegation, Lavrov said only that Moscow was giving Damascus "conventional weapons" related to air defense and asserted that the deal complied with international law.

Iranian Foreign Minister Ali Akbar Salehi said at the same news conference with Lavrov that Tehran and Moscow were "very close" on the Syrian issue.

Western and Arab nations, he said, "are sending weapons and forces to Syria, and are not allowing the reforms promised by the Syrian president to be applied."

Salehi said he is optimistic about the final results of the talks between Iran and 5+1 Group in Moscow.

Moscow is now trying to organize an international conference on Syria that would include several nations with influence over the conflict, including Iran.