Russia had evidence that the Syrian opposition possessed and used chemical weapons, a lawmaker said on Wednesday.

"There are reasons to presume that not only the Syrian government but also the militants possess chemical weapons," said Alexei Pushkov, head of the International Affairs Committee of the State Duma, or lower house of the parliament.

"There are suspicions that the militants have used these weapons repeatedly," he told a Duma plenary session.

Pushkov noted that the militants used chemical weapons near Aleppo in March and that was acknowledged by Carla Del Ponte, a member of the special independent commission of the UN investigating human rights violations in Syria.

"Russia has just passed existing proof to the UN Security Council," the Interfax news agency quoted him as saying.

Russia suggested Monday the Syrian government join the Organization for Prohibition of Chemical Weapons (OPCW) and put its chemical weapons under international control.

That proposal was confirmed accepted Tuesday as visiting Syrian Foreign Minister Walid al-Moualem said his country made the decision to "stave off an American aggression."