Berlin charges 'triple agent' with treason

German federal prosecutors have charged a suspected triple agent with treason and corruption, in a case that emerged during a furore over revelations of widespread US spying.

The 32-year-old, identified as Markus R., was employed by the German intelligence agency BND, but he was also spying for both the CIA and the Russian secret service, prosecutors said in charges laid at a Munich court on Thursday.

"The accused provided the CIA - in exchange for financial compensation - scores of documents and internal information," the federal prosecutor said in a statement.

Among the information sent electronically to the US agency in exchange for at least 95,000 euros ($A144,000) were details of people working for the BND's operations and foreign relations department.

According to local media reports, the documents included the names and addresses of BND agents, as well as information on the agency's own espionage plans.

The US was therefore able to get an idea of Germany's spying interests, the reports claimed.

The suspect also provided three documents to the Russian secret service in Russia's Munich consulate, prosecutors said.

Until his arrest on July 2, 2014, Markus R. was still working for the BND, which he joined in December 2007.

If convicted, he could face up to 15 years in prison.

The case had emerged in the wake of revelations the US had been carrying out widespread surveillance on communications.

The information emerging from documents made public by former CIA intelligence contractor Edward Snowden strained ties between Washington and Germany, a key European ally, and led to the expulsion of the US spy chief in Berlin.