Russia says it will veto a draft U.N. Security Council resolution to impose sanctions on 21 Syrian individuals, companies and organizations allegedly involved in chemical weapons attacks in the war-torn country.

The Security Council is due to vote Tuesday on the proposal drawn up by France, the United Kingdom and the United States which would also ban the supply of helicopters, which investigators say have been used in the attacks, to the Syrian government.

It comes as Russian President Vladimir Putin told a news conference Tuesday in Bishkek, the capital of Kyrgyzstan, that the draft resolution is “totally inappropriate.”

"It would undermine trust in the negotiating process. Russia will not support any new sanctions against the Syrian leadership,” said Putin, an ally of Syrian President Bashar Assad. His comments followed a meeting with Kyrgyz President Almazbek Atambayev.

The draft resolution follows a joint investigation by the U.N. and the Organisation for Prohibition of Chemical Weapons that said the Syrian air force and the Islamic State used chemical weapons during the 6-year-old civil war.

The report, published in Aug. 2016, said there was “sufficient evidence” that the air force twice attacked Syrian civilians with chlorine gas and the Islamic State used “sulphur-mustard” gas between 2014 and 2015.

At least 450,000 Syrians are estimated to have been killed and about 5 million have fled the country since the war started in 2011.