Whistle-blower Edward Snowden has offered to cooperate with German prosecutors and lawmakers in their effort to clear up all the details of the U.S. government's electronic spying on Berlin.

The former U.S. intelligence contractor made the offer in a letter to German Chancellor Angela Merkel.

Copies of that missive were distributed Friday to the press by German Green party lawmaker Hans-Christian Ströbele, who met the day before with Snowden in Moscow and agreed to deliver the document to Merkel.

Snowden, who obtained asylum in Russia after exposing the U.S. National Security Agency's targeting of the telephonic and Internet communications of tens of millions of private citizens in the United States and abroad, suggested he would be willing to appear before prosecutors or lawmakers in Germany.

But his Russian lawyer said Friday that Snowden could not leave Russia without jeopardizing his asylum status and risking extradition to the United States, where he faces charges under the 1917 Espionage Act.

Even so, Snowden's offer of help has provided a new twist in the controversy that erupted in Germany last week after it emerged that Merkel had been the target of spying, possibly by the U.S. Embassy in Berlin.

The German government on Friday cautiously welcomed Snowden offer.

Berlin "will find the way to make this conversation possible once Snowden is ready," Interior Minister Hans-Peter Friedrich said.

Shortly afterward, the government's spokesman, Steffen Seibert, qualified that statement.

The government does not meddle in the formation of parliamentary commissions or potential judicial processes because that falls outside the scope of its authority, Seibert said.

The co-chair of the parliamentary panel that oversees Germany's intelligence services said he favored seeking a way for Snowden to assist Berlin.

"If there's a possibility of hearing Snowden as a witness - without putting him in danger and without completely ruining relations between Germany and the United States - we should do it," Thomas Oppermann, a senior member of the main opposition Social Democrats, said on Twitter. EFE