Russia's Federal Security Service detained an Estonian diplomat based in St Petersburg, Mart Latte, on Tuesday as he was receiving confidential information from a Russian citizen, Interfax news agency reported.
"Measures in line with the norms of international law will be applied to the foreign diplomat," Interfax quoted the Federal Security Service, or FSB, as saying.
(Reporting by Andrey Ostroukh and Anton Kolodyazhnyy, editing by Mark Heinrich)
