Seventeen German journalists and several members of parliament are under investigation in the alleged leak of classified documents given to a parliamentary committee, the federal prosecutor's office said on Friday.
The documents related to a parliamentary inquiry into possible German government complicity in CIA prisoner flights and the detention of two men.
The president of the German parliament, Norbert Lammert, had sought charges against the journalists in June, senior prosecutor Simone Herbeth said, adding that an unidentified number of members were also under investigation.
"There is also an investigation in the direction of those entrusted with official secrets," Herberth said. "MPs [members of parliament] are also being looked at."
The president of the Federal Association of German Newspaper Publishers criticized the probe.
"It is not acceptable that journalists who are reporting about possible misdoing or errors have to fear persecution for giving away official secrets," Helmut Heinen said.
The journalists, among them reporters for national publications Sueddeutsche Zeitung, Der Spiegel, Die Zeit and Die Welt, are under investigation on suspicion of having published classified material that was the subject of a parliamentary committee.
The editor-in-chief of weekly Der Spiegel, who is under investigation together with four of the news magazine's reporters, called the inquiry an attack on freedom of the press.
"This seems to be an indiscriminate attack on press freedom," Stefan Aust was quoted as saying in the magazine's online edition.
The parliamentary committee is investigating the German government's possible complicity in the cases of CIA rendition flights that had layovers in Germany as well as the German secret service's activities in Baghdad during the US invasion in 2003.
The committee is also looking into the disputed kidnapping of Khalid el-Masri and the years-long detention of Murat Kurnaz.
El-Masri, a German citizen of Lebanese descent, says that he was seized in Macedonia on Dec. 31, 2003, and taken by CIA agents to Afghanistan, where he was allegedly abused before being released in Albania in May 2004.
Kurnaz, who was born in Bremen, Germany, but has Turkish citizenship, was detained in Pakistan in 2001, turned over to US authorities and held at the US prison camp at Guantanamo Bay as a terror suspect until his release last year.
Some opposition politicians had asked for the parliamentary committee to probe whether the German government looked the other way over practices such as the reported abduction. Some have accused German officials of delaying Kurnaz's release from Guantanamo.
In February, Germany's highest court ruled that authorities had violated press freedom in ordering a raid on the offices of a magazine that cited classified information in an article about the late leader of al-Qaeda in Iraq, Abu Musab al-Zarqawi.
The offices of the monthly Cicero were searched on Sept. 12, 2005, as investigators attempted to pinpoint the source of a leak of confidential papers from Germany's Federal Crime Office on the financing of Islamic extremists.