The German government says it is keen to hear directly from the fugitive NSA whistleblower Edward Snowden about the US spy agency's activities.
"If the message is that Mr Snowden wants to give us information then we'll gladly accept that," said German Interior Minister Hans-Peter Friedrich.
Mr Snowden's lawyer said a meeting could occur in Moscow, but not Germany.
The US Secretary of State, John Kerry, has said that in some cases, US spying has gone too far.
He said he would work with President Barack Obama to prevent further inappropriate actions by the National Security Agency.
Mr Snowden, 30, fled to Russia in June after leaking details of far-reaching US telephone espionage. He has temporary asylum, allowing him to live in Russia until next June.
In a surprise move, a German Green MP, Hans-Christian Stroebele, has met Mr Snowden in Moscow and revealed the former intelligence contractor's readiness to brief the German government on NSA spying.
Mr Snowden set out his position in a letter, which Mr Stroebele showed to reporters at a news conference on Friday.
The scale of the alleged US espionage has provoked international concern and calls for tighter supervision.
Asian countries have protested at claims that Australia was involved in a US-led spy network.
China has demanded an explanation of the reports, while Indonesia has summoned the Australian ambassador to Jakarta.
Reports that German Chancellor Angela Merkel's mobile phone was bugged by US spies for years overshadowed last week's EU summit and she remarked with irritation that spying on friends is "really not on".
According to Mr Stroebele, Mr Snowden is not keen on German investigators going to see him in Moscow, but would be ready to go to Germany if it could be guaranteed that he would not be extradited to the United States.
It is not clear whether Mr Snowden would get legal protection in Germany. The US authorities want to get him extradited to stand trial for revealing official secrets.
But the German government says it would welcome a meeting with the whistleblower.
"We will find a way, if Mr Snowden is willing to talk,'' Mr Friedrich said.
"Any clarification, any information and facts that we can get, is good."
In other developments:
- Major technology companies including Google, Apple and Yahoo have called for the US government to do more to rein in the NSA's activities
- Indonesia's foreign minister said reports that the NSA used Australian embassies to eavesdrop on Asian countries would indicate a "serious breach" of diplomatic rules.
Mr Snowden "will not go to Germany", his lawyer Anatoly Kucherena said. "This is not possible because he has no right to cross Russian borders.
"Within the framework of international agreements Snowden can give testimony in Russia but this should be decided by the German authorities."
But Mr Stroebele said there was a possibility that Mr Snowden could travel to Germany, the BBC's Stephen Evans reports from Berlin.
The Bundestag - the lower house of parliament - has the power to decree that someone addressing it has immunity.
Speaking to German ARD television, Mr Stroebele said that Mr Snowden "is fundamentally ready to help bring things to light".
"The conditions for that have to be established. We had a long discussion about that."
The MP said he had suggested that investigators could question Mr Snowden in Moscow about the NSA.
Mr Snowden "made it clear that he knows a very great deal," he went on.
Mr Stroebele described the former intelligence contractor as "amazingly talkative - he has a mission, an urge to communicate, he wants things to be put back on a legal basis".
Mr Snowden is starting work on Friday for a major private website in Russia, his lawyer has said.
Mr Kucherena would not disclose which site has employed Mr Snowden, citing security concerns. (BBC)