The Stuttgart Higher Regional Court on Tuesday sentenced a German-based couple to prison terms after finding them guilty of acting as Russian spy agents.

Andreas Anschlag was sentenced to six and a half years in prison while his wife Heidrun Anschlag was sentenced to five and a half years in prison. Both had been living with forged Austrian passports – their true identities are only known to the court.

According to prosecutors, the pair passed on hundreds of EU and NATO documents for decades, first at the behest of the Soviet Union and thereafter for its post-Soviet incarnation, the Russian Foreign Intelligence Service. They obtained the documents via their informant, a Dutch diplomat.

In April, a Dutch court sentenced the informant to 12 years in prison for delivering confidential documents to the agents.

Arrested in October 2011, the couple had been posing as Austrian nationals of Latin American origin. Outwardly they led an unremarkable life in Meckenheim, Germany a small town of 24,000 inhabitants.

When their trial opened in Stuttgart on January 15, 2013, federal prosecutors accused them of "secret agent activity" and of "forgery of documents."

hc/dr (AFP, AP, dpa)