East Germany's once-dreaded Stasi secret police kept files on numerous officials, even the country's former leader Erich Honecker, the chief federal prosecutor's office says.

German officials have examined the contents of a red suitcase once owned by Erich Mielke, the former Stasi chief, and found they contained documents pertaining to Honecker.There have been news reports that Mielke intended to use the documents to blackmail Honecker.

ZDF television quoted East Germany's former chief prosecutor, Hans-Juergen Josef, as saying the documents showed Honecker had testified against other communists when he was convicted of treason by a Nazi court in 1937.

Honecker was tried along with other communists during Nazi purges before World War II, and sentenced to 10 years in jail.

A statement from the German federal prosecutor's office said "examination of the suitcase documents produced no evidence of active cooperation by Erich Honecker with the Nazi regime."

Honecker, 78, is confined to a Soviet military compound outside eastern Berlin. Miekle, 82, is under arrest. Officials are investigating Honecker, Mielke and other former top officials for corruption, abuse of power and other charges.

East Germany's Stalinist regime was overthrown in last year's peaceful revolution.