Fugitive US intelligence leaker Edward Snowden was Friday set to meet with leading Russian rights activists and lawyers at the airport in Moscow where he has been stuck in transit for nearly three weeks.

Several campaigners told AFP they will attend the afternoon meeting after receiving an emailed invitation apparently from Snowden, in what is set to be be the former government contractor's first public encounter since he arrived on a flight from Hong Kong last month.

According to the invitation which was posted on social media by one activist, the fugitive wants to discuss his "next steps" as he seeks to escape US authorities after leaking details of massive American intelligence surveillance.

In his message he thanked Latin American states for considering an application for asylum but denounced "an unlawful campaign by officials in the US Government to deny my right to seek and enjoy this asylum."

Those invited to attend the meeting at Moscow's Sheremetyevo airport at 1300 GMT include representatives of Amnesty International, Human Rights Watch and Transparency International as well as several prominent lawyers working in Moscow.

"I can confirm that Mr Snowden will hold a meeting with rights representatives on the territory of the airport," Sheremetyevo spokeswoman Anna Zakharenkova told AFP.

"We will provide access and premises," she added, declining to provide further details.

Snowden has made no public appearances since arriving at the state-controlled airport in the Russian capital on June 23. According to officials, he has spent the whole time in the airport transit zone but there has not been a single verifiable sighting of him.

He has asked the activists to meet in the arrivals hall of Terminal F where "someone from airport staff will be waiting there to receive you with a sign labelled 'G9'."

Sergei Nikitin of the Moscow branch of Amnesty International told AFP he received an email inviting his group and said "we are planning to go."

Elena Panfilova of Transparency International said the "somewhat unexpected" invitation was being discussed by her organisation.

Tatyana Lokshina of Human Rights Watch in Moscow said on her Facebook page that she had also received an invitation from Snowden. While she could not yet confirm "it was real", Lokshina said she was going to the airport.

She posted the full email where Snowden purportedly said he wanted to have the meeting for "a brief statement and discussion regarding the next steps forward in my situation."

Leftist Latin American states are seen as the most likely destination for Snowden, who has applied for asylum in 27 countries. Bolivia, Venezuela and Nicaragua has all expressed readiness to consider giving Snowden asylum.

The Snowden email said the efforts by the US authorities to apprehend him represented a threat to "the basic right shared by every living person to live free from persecution."

Kristinn Hraffnson, spokesman for the WikiLeaks anti-secrecy website which is supporting Snowden, told AFP that he could not confirm that the meeting was planned.

The Interfax news agency said Russia's human rights ombudsman Vladimir Lukin had been invited and was willing to attend.

Prominent Moscow lawyer Genrikh Padva -- one of several lawyers invited -- confirmed to AFP that he had received the invitation, but did not believe he would have time to attend.

A source had told Interfax a day earlier that the United States and Russia were now in "wait-and-see" mode over Snowden, indicating that a rapid solution to his presence in Moscow may not be in sight.

President Vladimir Putin has vowed that Moscow will not extradite Snowden but also indicated the Kremlin is keen to see the back of a man who has added an additional problem to already strained relations with Washington.

The meeting comes after the United States on Thursday told China it was upset it did not hand over Snowden after he fled to Hong Kong, saying that the decision had undermined relations.

President Barack Obama, meeting senior Chinese officials who were in Washington for annual talks, "expressed his disappointment and concern" over the Snowden case, the White House said.