Russia is amassing troops and weaponry near Ukraine’s eastern border, a move some say is a strategic show of force.
Russia has ordered a Ukrainian diplomat to leave the country after allegedly receiving classified information from a database of the country’s main security agency, and Ukraine responded by expelling a Russian diplomat.
Oleksandr Sosoniuk, the Ukrainian consul in St Petersburg, was detained on Friday while meeting with a Russian in which he obtained material from a database of the Federal Security Service (FSB), the agency said.
On Saturday, the Russian foreign minister informed charge d’affaires Vasily Pokotilo that Sosoniuk must leave the country by Thursday. No details about the contents of the classified material were made public.
The Ukrainian foreign ministry later said it has ordered a senior Russian diplomat to leave.
The FSB earlier said Sosoniuk had been caught “red-handed” during a meeting with a Russian national as he sought to receive “classified” information.
“Such activity is not compatible with his diplomatic status and is of clearly hostile nature towards the Russian Federation,” the FSB said.
“In conformity with international law, measures will be taken against the foreign diplomat.”
The expulsions come amid escalating tensions over Russia’s military buildup along the border with the eastern Ukraine region that is under the control of Russia-backed separatists.
Ukraine’s foreign ministry said Sosoniuk was held for several hours but was now back at the country’s consulate in St Petersburg.
In recent years, Russia has detained a number of Ukrainian nationals on suspicion of spying but the detention of a diplomat is rare.
“An incident like this, the detention and now seemingly the expulsion of this diplomat, can only make matters worse and increase tension in this region even more,” Al Jazeera’s Charles Stratford said, reporting from Kyiv.
Kyiv has been battling Russian-backed separatists in the east of Ukraine since 2014, and clashes have intensified since the start of the year, shredding a ceasefire agreed in last July.
On Friday, Ukrainian President Volodymyr Zelenskyy pressed for peace negotiations.