Britain on Monday imposed sanctions on two Russian research institutes and senior staff it said were linked to Moscow's chemical weapons program and involved in developing toxins used to poison Russian opposition activist Alexei Navalny.

The sanctions, cast by Britain as a way to expose and deter Russia's use of chemical weapons, come ahead of the NATO summit in the Turkish capital Ankara and after a similar move by the European Union.

In 2020, Navalny fell seriously ill on a flight in Siberia and Western laboratories concluded he had been poisoned with a Novichok nerve agent, a class of military-grade nerve agents developed during the Soviet era.

In 2024, Navalny died after being poisoned with Epibatidine, a toxin from poison dart frogs, Britain and other European allies have said. Russia denied accusations it was behind that death.

The British government said on Monday that those sanctioned were involved in developing the Novichok agent and Epibatidine.

A harlequin poison dart frog (Oophaga anchicayensis) is pictured at the Tesoros de Colombia (Treasures of Colombia) sustainable farm in Nocaima, Cundinamarca department, Colombia, on July 9, 2024.
A harlequin poison dart frog (Oophaga anchicayensis) is pictured at the Tesoros de Colombia (Treasures of Colombia) sustainable farm in Nocaima, Cundinamarca department, Colombia, on July 9, 2024. (credit: Raul Arboleda/AFP via Getty Images)

Russia's embassy in London did not immediately respond to a Reuters request for comment on the new sanctions.

Russia has allegedly used chemical weapons in the past, violating international law

Foreign minister Yvette Cooper said Russia's "repeated use of chemical weapons" was a violation of international law and a threat to global security.

"From the use of Novichok nerve agents in Salisbury to Epibatidine in Siberia, poisoning Dawn Sturgess and Alexei Navalny, Russia continues to use barbaric tools to inflict death and suffering on innocent civilians, including in Ukraine," she added.

Novichok was also used in the 2018 poisoning of former Russian double agent Sergei Skripal and his daughter Yulia in Salisbury - an attack that they survived, but which led to the death of a civilian, Sturgess, who later came into contact with a discarded container of the substance.

A British public inquiry concluded last year that Russian President Vladimir Putin must have ordered the attack by GRU intelligence operatives on Skripal.

Russia has always denied any involvement in that incident, casting the accusations as anti-Russian propaganda.