Spanish police have arrested four people for alleged sanctions breaches for shipping chemicals to Russia that could have been used to make weapons or nerve agents.

The four, including three Russians, were arrested in the Mediterranean cities of Barcelona and Girona and 13 tonnes of chemicals were seized at the port of Barcelona in an operation codenamed “Test Tube”, according to Spanish police and the European Union anti-fraud agency, OLAF.

Police said a Spanish company run by Russians was behind the shipments and used front companies in Armenia and Kyrgyzstan to disguise where the chemicals were going.

The shipments never ended up in those countries and were instead moved overland to Russia, said the Spanish police. The company, which was not identified, had a subsidiary in Moscow, they added.

The company was responsible for previous shipments that the authorities said could have been possible precursors for chemical weapons or nerve agents.

The shipments were banned under sanctions introduced following the Russian invasion of Ukraine in February 2022, according to the police and OLAF.

The chemicals seized at the port of Barcelona that were bound for Russia. Photo: OLAF

Ville Itala, the director-general of OLAF, said: “Sanctions are only as effective as their enforcement, and we are proud to contribute actively.”

Police said they were looking to investigate others involved in the smuggling network and to make more arrests.

Russia claims that it had destroyed all of its chemical weapons stockpiles in 2017. But the US has contested the claim, pointing to the 2018 assassination attempt in the UK on Sergei Skripal, a double agent for Britain, using a novichok nerve agent.

“The US also has concerns about reports that Russia has used other chemical agents against Ukrainian armed forces,” the US State Department said in a report in April.

Russia described the claims as “absolutely groundless” and suggested that footage used to support the case could have been from smoke grenades, which are not banned.