Prosecutors say a court in Estonia has sentenced three cigarette smugglers to prison for spying for Russia in a rare low-level espionage case.

The state prosecutor's office said Tuesday that the men, aged between 21 and 42, received sentences varying from 2 years to 4 years and 10 months "for crimes against the Republic of Estonia." That included supplying observations to Russian security services on Estonia's defense forces, border and security operations.

Estonian officials said the men didn't have access to state secrets, but had been recruited by Russia's domestic security agency FSB in an apparent deal where Russian officials would turn a blind eye to the men's criminal activities in exchange for information.

The sentences were delivered in closed door trials between October last year and this month.