There are 180km (113 miles) of Stasi files

The former chancellor says opening up the files - which contain reports from Communist bloc spies and transcripts of intercepted telephone conversations - would violate his privacy.

The court agreed that he deserved protection as the victim of illegal Stasi eavesdropping.

The ruling means the archive can no longer release records on someone without that person's explicit consent.

Journalists and historians are keen to see Mr Kohl's Stasi records, which it is thought may shed light on a party financing scandal that has damaged his reputation and that of his Christian Democratic Union party.

The head of the Stasi archive, Marianne Birthler, argued that closing the files would prevent Germany coming to terms with its past, and would allow other prominent Germans to block the publication of documents.

"In a lot of cases these persons will not agree to the usage of their files and therefore I find this judgement a great damage for our reappraisal of a dictatorship," she said after the ruling.

She has urged parliament to re-write the law to prevent the archives being permanently closed.

The files of skating star Katarina Witt have been temporarily sealed

The BBC's Berlin correspondent, Rob Broomby, says the court's decision is likely to cause dismay in eastern Germany.

He says the German Interior Minister, Otto Schilly, has taken Mr Kohl's side in the debate that has raged over the last two years, and that parliament is unlikely to respond to Ms Birthler's appeal.

Mr Kohl's own government had passed the legislation which allowed the release of Stasi files on other prominent Germans.

Mr Kohl was the nation's longest-serving post-war leader and he became the chancellor of German unity. As such, he was subject to intense scrutiny from the Stasi.

He has argued that the files are bound to contain false information.

Last month, Olympic figure skating star Katarina Witt won a temporary injunction against the publication of her file. The skater, who won gold for East Germany in 1984 and 1988, argued that she was a victim of the Stasi.