A Russian diplomat was expelled from Sweden for actions "not in line with the Vienna Convention," which governs diplomatic protocol, said Sweden's Foreign Affairs Ministry on Monday.

In apparent retaliation over the move, Russia later expelled a Swedish diplomat.

"Russian authorities have informed us that a diplomat at the Swedish embassy has to leave the country…Russia has made it clear it considers this to be a response to the Swedish decision to expel a Russian diplomat," Foreign Ministry spokesman Johan Tegel told AFP news agency.

The names of the diplomats were not provided to the press, nor were the dates of the expulsions.

"I can only say it was recently," Tegel noted.

Tensions between the countries have been high in recent years.

Swedish Defense Minister Peter Hultqvist said in June that Sweden was increasing its military capabilities and exercises with allies in response to the resurgence of Russia's military might, reported AFP.

In May, Sweden - a non-NATO member - played host to the "Arctic Challenge," a cross-border aerial military exercise between NATO and its allies.

Last year, the presence of a foreign submarine thought to be Russian was discovered in Swedish territorial waters near Stockholm, prompting the country's largest military mobilization since the Cold War.

ls/cmk (AFP, Reuters)