Russia has been accused of using chemical weapons in Ukraine in a flagrant breach of international law. The claim, made on social media by the Naval Forces of the Armed Forces of Ukraine, comes days after an expert claimed Vladimir Putin could start using novichok on civilians in the country, as indeed he did in the UK in 2018.

A Facebook post shared yesterday said: “The occupiers are dropping chlorpicrin grenades from drones on our defenders in the east. 

“In order to protect themselves from the strong irritant effect of the prohibited ammunition, the marines held their positions in chemical defences.”

Footage of an alleged K-51 grenade was shared via Euromaidan Press yesterday.

The K-51 produces CS gas or a direct equivalent although its precise chemical composition is unknown.

Symptoms are a burning sensation, tears, coughing, shortness of breath and incapacitation for between 20 and 30 minutes.

A Chemical Weapons Convention in 1993 backed by Russia banned the use of riot control agents such as CS gas on the battlefield, while permitting them for handling civil disturbances. 

Speaking to Forbes last month, Political scientist and East Europe specialist Sergej Sumlenny said of their apparent use: “They try to push the limits of the possible. They distort and erase the limits of legality.”

On November 24, Oleksiy Gromov , deputy chief of the main operational department of the General Staff of the Armed Forces of Ukraine, stressed there was no specific information about an imminent chemical attack.

He explained: “Undoubtedly, they have chemical weapons, they have RHC defense units on the territory of Ukraine that can use chemical weapons. 

“But the intelligence currently does not confirm that the Russians are mass transporting ammunition with poisonous substances.”

However, speaking at the weekend, Dr Neil Bradbury, a US-based expert in poisonous substances, said Putin could opt to use the deadly nerve agent novichok, just as he did in Salisbury in an attempt to assassinate Russian double agent Sergei Skripal four years ago.

He said: “Whilst it is very lethal and kills quickly and easily, in terms of battle use and against troops it probably isn’t that effective.

“Certainly for troops that wear chemical warfare suits, they’re going to be protected. There’s also a very good antidote that troops generally carry.

“Unfortunately, nerve agents tend to have their use targeting civilian populations.

“It’s more used as a terror weapon to frighten, rather than an agent directly against troops.”

Dr Bradbury, author of  A Taste for Poison: Eleven Deadly Substances and the Killers Who Used Them, added: “People start drowning in their own fluids and the heart rate goes completely out of whack because of the interference with the neural regulation. It’s a really nasty chemical.

“It is very scary. Technically Russia is a signatory to the Chemical Weapons Convention, but to what extent that has an impact I don’t know.”