The protest raised by the Organization for Security and Cooperation in Europe (OSCE) on Thursday is the latest aimed at ending an inquiry into German journalists accused of publishing classified government information.

"Initiating proceedings against the media merely in retaliation for their publishing, with the aim of deterring them from similar editorial decisions, is inadmissible in a society proud of its press freedoms," OSCE media watchdog chief Miklos Haraszti said in a statement sent to the German Justice Ministry.

"I call on the German authorities to stop prosecuting the journalists and ensure that media professionals can continue informing the public of important matters without intimidation."

'More holes than Swiss cheese'

The investigation was launched by Siegfried Kauder, a parliamentary leader in Chancellor Angela Merkel's Christian Democratic Union, who said the chancellery had threatened to deny information to a parliamentary committee charged with overseeing the BND intelligence agency after journalists quoted from classified files.

"All the sudden the investigatory committee had more holes than Swiss cheese," he told German public broadcaster ARD last week. "You could read more from the classified files in the press than we had in the committee."

The decision to conduct an investigation of the press sources met with approval from other CDU members, including Jürgen Gehb.

"Journalists should not be deemed sacrosanct," he told the daily Kölner Stadt-Anzeiger on Thursday, adding that investigators were right to use all the powers at their disposal to expose leaks of the classified reports.

Opposition: Press deserve protection

German opposition parties as well as some members of Merkel's grand coalition have, however, complained that the investigation violates press freedom by targeting journalists instead of the people giving files to the press.

Wolfgang Thierse, vice-president of the German Bundestag and a member of the Social Democratic Party, called Thursday for increased legal protection for the press to be enacted in Germany to "slow down hasty investigations and brash prosecutors," he told the daily Berliner Zeitung.

Max Stadler, member of the free-market liberal FDP, said Thursday that his party planned to introduce a bill in parliament after the summer break that would exclude the press from investigations into government security leaks.

"It is not right to start criminal investigations into journalists who have a duty to provide information to the public and are not subject to security clearance regulations," he told reporters in Berlin.

In a similar case decided in February, Germany's Constitutional Court ruled against prosecutors who confiscated information from the monthly magazine Cicero in an attempt to track down who leaked the classified data that was printed in the magazine.

The court said raids against the press to investigate government leaks were unconstitutional.