Germany's security chief wants to arrange a meeting with NSA whistleblower Edward Snowden if he is willing to provide details about the agency's activities including the alleged surveillance of Chancellor Angela Merkel's mobile phone.

The comments by Interior Minister Hans-Peter Friedrich came after a German opposition MP travelled to Moscow and met Mr Snowden. Hans-Christian Stroebele, said he received a letter from Mr Snowden to German authorities that he released on Friday.

In the letter Mr Snowden, who faces espionage charges in the US, indicated that he will not speak with German officials until the United States stops its prosecution of leakers like him.

"Though the outcome of my efforts has been demonstrably positive, my government continues to treat dissent as defection, and seeks to criminalise political speech with felony charges that provide no defence. ... I am confident that with the support of the international community, the government of the United States will abandon this harmful behaviour," Mr Snowden wrote in the letter.

"I look forward to speaking with you in your country when the situation is resolved, and thank you for your efforts in upholding the international laws that protect us all," he said.

Mr Stroebele, a Green party member, is a prominent critic of the NSA's alleged activities.

The release of the letter came after Mr Friedrich said: "If the message is that Mr Snowden wants to give us information, then we will be glad to accept that."

He said that "we will find a way to make a conversation possible if Mr Snowden is prepared to talk to German officials."

Mr Friedrich's spokesman, Jens Teschke, said he understood him to be referring primarily to the possibility of officials speaking to Mr Snowden in Russia, where he has been granted asylum.

Germany is seeking answers from US authorities to allegations that Mrs Merkel's mobile was monitored, which prompted the German chancellor to complain to President Barack Obama last week. Her foreign policy adviser and intelligence co-ordinator held talks on the issue in Washington on Wednesday.

Germany's government, along with many others, rejected an asylum request from Mr Snowden earlier this year.

Mr Teschke said that, if Mr Snowden now wanted asylum in Germany, he would have to come to the country and then apply for it - but noted that Germany has an extradition treaty with the United States.

German federal prosecutors are looking into whether there are grounds to investigate the allegations regarding Mrs Merkel's mobile, but it is unclear when they might decide. Germany's parliament is expected to discuss the NSA's alleged activities on November 18.

Thomas Oppermann, an MP who heads a parliamentary panel that oversees German intelligence, said on Twitter that if there's an opportunity to hear Mr Snowden as a witness without endangering him and without "completely ruining" German-US relations, it should be taken.

Mr Snowden was granted asylum in Russia in August after being stuck at a Moscow airport for more than a month following his arrival there from Hong Kong. The 30-year-old faces espionage charges in the US.

AP