The Russian FSB security service said he had detained a Ukrainian diplomat and accused him of receiving sensitive information from a Russian citizen.
In recent years, Russia has detained a number of Ukrainian citizens on the grounds of espionage, but the detention of a diplomat is rare and is seen as a sign of strong rising tensions.
“A Ukrainian diplomat, a consul of the Ukrainian consulate general in St. Petersburg, Alexander Sosonyuk, has been detained by the Russian FSB,” the security service said with the Russian spelling of his name. He was detained Friday, the FSB said.
Kiev confirmed that the diplomat had spent several hours in detention and was now back in the Ukrainian diplomatic mission.
The FSB said Sosonyuk was caught red-handed during a meeting with a Russian citizen because he wanted to receive “classified” information.
“Such activities are not compatible with its diplomatic status and are clearly hostile to the Russian Federation,” the FSB said. “In accordance with international law, measures will be taken against the foreign diplomat.”
In Kiev, Oleg Nikolenko, spokesman for Ukraine, the incident led to increasing tensions between the two countries. “This is another provocation amid Russia’s destabilizing activities,” he told Agence France-Presse in a statement.
He said Kyiv had investigated the incident and would respond in the near future.
Tensions between Russia and Ukraine have escalated in recent weeks, with Kyiv accusing Moscow of joining forces at its border and trying to destroy ‘Ukrainian state capture’.
Kiev has been dealing with Russian-backed separatists in eastern Ukraine since 2014, and the clashes have intensified since the beginning of the year and shattered a ceasefire agreed last year.
Concerns are mounting that the long-running conflict could turn into a wider battle again, and Ukrainian President Volodymyr Zelenskiy has called on the West for help.