Former intelligence agency contractor Edward Snowden said U.S. officials have been waging a campaign to prevent him from taking up offers of asylum, he said in a letter sent to a Human Rights Watch official and posted on Facebook.

In the letter, he said he had invited human rights groups to meet on Friday afternoon at Sheremetyevo Airport, where he has been in limbo since he flew from Hong Kong to Moscow on June 23, to discuss "next steps forward in my situation".

In a separate email to Reuters, Snowden confirmed that the meeting with human rights groups would go ahead but said it would be closed to the press. He said he planned to speak to the media later.

"I can confirm that such a meeting will take place," said an airport spokeswoman, adding that the meeting would take place in the second half of the day.
Snowden, wanted by Washington on espionage charges for divulging details of secret U.S. surveillance programs, flew to Moscow on June 23, and has not left the airport transit area despite offers of asylum from three countries.

Human rights groups Transparency International and Amnesty International confirmed they had received emails inviting them to a meeting at the airport. Interfax reported that Human Rights Watch and other groups were also invited to the meeting.

"Yes, I have received a brief email. It said that he would like to meet with a representative of a human rights organization - there was not much information there. I'm planning to go," said Sergei Nikitin, the head of Amnesty International Russia.

President Vladimir Putin has said Snowden should choose a final destination and go there as soon as possible, but it is unclear how he would get to any of the Latin American countries that have offered him asylum.