Experts have succeeded in breaking the code of magnetic tapes used by the former East German secret police which contain names of thousands of agents, according to two German magazines.

The tapes reveal secrets of 63,000 espionage operations and include the aliases of more than 15,000 Stasi agents in the former East and West Germany.

Der Spiegel and Focus magazines say the data covers the beginning of the Cold War in the 1950s and ends on 23 December 1989, after the fall of the Berlin Wall.

Only about a third of the agents have been identified, Der Spiegel reports.

The records also apparently reveal details of intelligence gathering operations on some 1,500 targets including ministries, businesses and political parties and groups on both sides of the Iron Curtain.

The Stasi, or Ministry for State Security (Staatsicherheit), was created in 1950 by German communists in the Soviet zone of occupied Germany and was disbanded in 1989.

Responsible for both domestic political surveillance and foreign espionage, it soon earned a reputation for effectiveness. It extensively penetrated West Germany's governing circles and military and intelligence services.

Der Spiegel says the Gauck Commission, which administers Stasi records, has passed the experts' findings to the Interior Ministry and Chancellor Gerhard Schröder's office.

Focus adds that Germany's chief prosecutor has opened 12 new judicial inquiries into suspected former Stasi agents