Russia and Estonia have exchanged two convicted spies over a bridge separating the countries.

Estonian security official Eston Kohver was sentenced to 15 years in a Russian jail last month.

He was swapped for Aleksei Dressen, who was imprisoned in Estonia in 2012 on charges of spying for Moscow.

Kohver's case provoked a diplomatic row, with Estonia and the EU insisting he was abducted from Estonian soil, a charge Russia denied.

Dressen was a former officer in Estonia's security police, who was found guilty of passing secret data to Russia for years after Estonia's independence in 1991.

He had been arrested in 2012 along with his wife, Victoria Dressen, who was given a suspended sentence.

According to the Russian Federal Security Service, the swap took place on a bridge over the Piusa River that separates Russia's western Pskov region and Estonia's Polva county.

The exchange came after "long-term negotiations", the head of Estonia's Internal Security Service, Arnold Sinisalu said at a televised news conference, sitting alongside Kohver.

The Estonian agent said he was glad to be back home and thanked "all the authorities who helped me get back to Estonia, who helped me to, so to say, endure in prison".

Relations between Russia and its Baltic neighbours have been uneasy since they joined Nato and the European Union in 2004.

They have worsened since the crisis in Ukraine, where Russia is accused of arming separatists in the east - which Moscow denies.