Iran accused Ukraine on Saturday of attacking one of its merchant vessels in the Caspian Sea, killing a sailor and wounding another, and warned it would not leave the incident unanswered.

The accusation came after Ukrainian President Volodymyr Zelensky said Kyiv had carried out long-range strikes in the Caspian Sea against vessels involved in transporting military cargo involving Iran, underscoring the increasingly international dimensions of Russia’s war in Ukraine.

Iran’s foreign ministry said the attack on Saturday morning caused the ship “to explode, killing one sailor and injuring another”, according to the official IRNA news agency.

The Islamic republic “has never intervened in the conflict between Russia and Ukraine”, it asserted.

On Saturday, Zelensky said on social media that armed forces had achieved “very strong results with long-range strikes in the Caspian Sea including vessels used in military cargo shipments involving Iran, as well as a warship”.

Ukraine’s intelligence services (SBU), for their part, reported on Telegram that drone attacks had been carried out against “cargo vessels under international sanctions that were used to transport military cargo between Iran and Russia”.

According to Iranian state television, the foreign ministry summoned the Ukrainian charge d’affaires in Tehran on Saturday to protest this “hostile and criminal act”.

In a conversation with the European Union’s foreign policy chief Kaja Kallas, Iranian Foreign Minister Abbas Araghchi called for a “firm response” by the EU and the United Nations Security Council to this attack, IRNA added.