Russia will provide the UN Security Council with evidence that the August 21 chemical attack in a Damascus suburb was perpetrated by the rebels, Russian Foreign Minister Sergey Lavrov said Wednesday.

“We have plenty of reports on chemical weapons use, which indicate that the opposition regularly resorts to provocations in order to trigger strikes and intervention against Syria,” Lavrov was quoted by the state-run Russia Today news network as saying. “There’s a lot of data. It’s widely available on the Internet. This data is presented in the report, which our experts put together in association with the use of chemical weapons in Aleppo in March this year. There’s also plenty of data on the incidents that occurred in August in Ghouta, near Damascus.”

Lavrov said he has not yet seen the evidence but he’s “sure that the experts are going to work with it and, of course, we’ll provide it to the Security Council.”

According to the head of the Kremlin administration, Sergey Ivanov, the ammunition used in the August 21 attacks were “backyard produced,” he told RT.

Earlier Wednesday, Syria turned over materials to Russia which aimed to show that a chemical weapons attack last month was carried out by the rebels, a top Russian diplomat visiting Damascus said.

Deputy Foreign Minister Sergei Ryabkov said Syria told Russian officials the material “bears witness to the rebels participating in the chemical attack” but that Russia has not yet drawn any conclusions.

Ryabkov was meeting Wednesday with Syrian President Bashar Assad, Russian news agencies reported.

Assad’s office released a statement after the meeting saying that “President Assad expressed… his gratitude to Russia for its position of helping Syria face down the savage attack… and the Western, regional and Arab-backed terrorism.”

“Russia’s positions on the Syrian crisis create hope of a new global balance,” Assad said in the statement cited by AFP.

Ryabkov called the UN report on chemical weapons use released earlier this week “one-sided” and “political.”

“We are disappointed, to put it mildly, about the approach taken by the UN secretariat and the UN inspectors, who prepared the report selectively and incompletely,” Ryabkov told the state-run Russian news agency RIA in Damascus.

“Without receiving a full picture of what is happening here, it is impossible to call the nature of the conclusions reached by the UN experts … anything but politicized, preconceived and one-sided.”

Russia has been Syria’s main ally since the start of the conflict in March 2011, blocking proposed UN resolutions that would impose sanctions on Assad’s regime and opposing an attempt to authorize the use of force if Syria does not abide by the agreement to get rid of its chemical weapons.

On Monday, UN inspectors said there was “clear and convincing evidence” that chemical weapons were used on a relatively large scale in the August 21 attack. The findings (click here to read the full report) represent the first official confirmation by scientific experts that chemical weapons were used in Syria’s civil war, but the report left the key question of who launched the attack unanswered.

Hours after the report was released, US officials said the results clearly show that the government of Bashar Assad was behind the August 21 attack on a Damascus suburb in which more than 1,400 people were killed, according to US figures.

The US, the UK and France are convinced the Assad regime is behind the use of chemical weapons while the Russians have consistently blamed the rebels.

The fighting in Syria has killed more than 100,000 people, according to activists and the UN, and has forced seven million to flee their homes

AP contributed to this report.