A Russian court has convicted an Estonian businessman of espionage and sentenced him to 12 years in prison.

The case against Raivo Susi was classified as "top secret" and the trial, which ended on December 11, was held behind closed doors.

Susi was arrested in February 2016 at a Moscow airport while on his way to a Central Asian country.

Susi's lawyer, Aleksei Toplygin, told reporters that his client's case stemmed from his activities in 2004-07.

Susi is a co-owner of two companies involved in the sale and repair of aircraft.

Susi's sentence was pronounced a month after Estonia's Prosecutor-General's Office said it detained a man suspected of being a Russian national on suspicion of espionage.

In 2015 and 2016, three men in Estonia were convicted of cooperating with Russian intelligence services and sentenced to prison.

In May, Estonia expelled two Russian diplomats posted at Moscow's consulate in Narva over contacts with local officials that were considered inappropriate for diplomats.

Occupied by the Soviet Union during World War II, Estonia gained independence in the Soviet collapse of 1991 and is now a member of NATO and the European Union.

Based on reporting by Rapsinews and Interfax