Fugitive US intelligence leaker Edward Snowden will on Friday 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 have told AFP they will attend the 1300 GMT meeting after receiving an invitation from Snowden, in what will be the former government contractor's first publicised encounter since he arrived on a flight from Hong Kong.

According to the purported invitation from Snowden posted on social media by one activist, the fugitive wants to discuss his "next steps" forward.

He also rails against the "unlawful campaign" against him by Washington which is seeking his extradition after he leaked details of pervasive US intelligence surveillance

Those invited included 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.

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. She said the email had come from an apparently secure email address in Snowden's name.

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

She quoted the email as saying Snowden wanted to have the meeting for "a brief statement and discussion regarding the next steps forward in my situation."

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 email 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."

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.

Prominent Moscow lawyer Genrikh Padva confirmed to AFP that he had received an invitation for a meeting at the airport Friday afternoon, but did not believe he would have time to attend.

Olga Kostina, a rights activist who is a member of Russia's public chamber advisory body, told the state ITAR-TASS news agency that she would attend "if just out of curiosity".

Interfax said Russia's human rights ombudsman Vladimir Lukin had been invited and he told the agency he was ready to attend the meeting.

A source had told Interfax the 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 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.