Russia says it has unmasked a network of spies who allegedly passed intelligence information to Israel.

It said they had worked under the cover of an Israeli organisation set up to maintain contact with Jews in the former Soviet Union and eastern Europe.

A regional official of the Russian Federal Security Service Sergei Savchenkov described the activities of the Israeli bureau as an "extremely perfidious" espionage operation.

He said the spy network was exposed last year when the Russians arrested a man who admitted giving details of a new battle tank to the Israeli bureau known as Nativ.