The US has accused Russia of deploying chemical weapons as a “method of warfare” in Ukraine, in violation of international laws banning their use.

State department officials said Russia used the choking agent chloropicrin to win “battlefield gains” over Ukraine.

The allegations, which US officials said were not an “isolated” incident, would contravene the Chemical Weapons Convention (CWC), which Russia signed.

The Kremlin rejected the accusations, calling them “baseless”.

Spokesman Dmitry Peskov told reporters in Moscow that Russia stood by its obligations under the CWC, which prohibits states from developing or acquiring new weapons. Some 193 states have ratified the convention.