A court in Russia has sentenced Estonian security official Eston Kohver to 15 years in prison for espionage and other charges.
Kohver was detained at the Russian border on last September in a case that provoked a diplomatic row.
Russia’s domestic security service, the FSB, said he was on a “spying operation” on Russian territory.
But Estonia denied the accusation and says its officer was “abducted” on Estonian soil.
After his arrest for spying on 5 September last year, Kohver was charged with other crimes including smuggling arms and illegally crossing the Russian state border, according to Interfax news agency.
The Estonian foreign ministry condemned Wednesday’s verdict, saying it constituted a “blatant breach of international law”.
The dispute comes amid heightened tensions between Estonia and Russia.
In 2004, the Baltic state joined Nato and the EU. Both bodies accuse Russia of directly helping separatists in eastern Ukraine with regular troops and heavy weapons. Russia denies the claims.