The authorities in Belgiam have located three caches of Soviet KGB radio equipment hidden in woods outside Brussels after a tip-off by British secret services.

The tip-off was based on KGB archives smuggled out by the Soviet defector, Vassili Mitrokhin.

It's unclear when the radio transmitters were hidden; they were found in November but their discovery has only been revealed now.

According to Vassili Mitrokhin, a former KGB archivist, Soviet spies buried explosives and other equipment across Europe and the United States at the height of the Cold War for sabotage purposes.