The Stasi had thousands of records on prominent West Germans

The head of the office, Marianne Birthler, said that journalists and researchers who sought access to the records would be allowed to see them.

Eleven of the 16 politicians spied on by former East German agents are dead.

The documents cover a Cold War period shortly before Chancellor Willy Brandt resigned in 1974 after one of his aides had been exposed as a Stasi spy.

German media report that a file on Brandt, who was the Social Democrat leader, is among those being released, covering the period 1969-1972.

Another one is reportedly that of the former conservative premier of Bavaria, Franz Josef Strauss.

They are not among those suspected of having been informers for the former communist secret police.

They could be informal collaborators, they could be people who were used or people the Stasi collected information on Marianne Birthler, Head of Stasi Records Office

Massive archives

She said the documents on the 16 politicians were registered with a code which makes it difficult to establish if they had knowingly collaborated.

"They could be informal collaborators, they could be people who were used or people the Stasi collected information on," she said.

Eleven other German politicians have been told that the Stasi kept files on them which could be released in the coming weeks, if they do not request otherwise.

The records are part of the so-called Rosenholz archives which were seized by the CIA after the fall of the Berlin Wall in 1989.

The US is gradually returning the documents to Germany.

They contain microfilms of about 300,000 personal files, as well as more than 50,000 records of Stasi operations.

The archives have revealed the extent to which East German secret police spied on West German politicians during the Cold War.