US whistleblower Edward Snowden has said he wants asylum in Russia until he can legally travel on to some of the Latin American countries that have offered him asylum, adding that he has "no regrets" about leaking a US spying programme.

Snowden, who has been holed up in transit zone of Moscow airport since June 23, told rights activists on Friday that he was prevented by Western governments from flying to the Latin America.

The former National Security Agency contractor said he was submitting a request to stay in Russia "until such time as these [Western] states accede to law and my legal travel is permitted", according to a transcript of his remarks released by anti-secrecy website WikiLeaks.

Snowden is serious about obtaining political asylum in the Russian Federation. Vyacheslav Nikono, pro-Kremlin lawmaker

The meeting at Sheremetyevo airport with rights groups and lawyers appeared to be an attempt by Snowden to find a way out of an increasingly difficult situation as he seeks to escape US espionage charges for leaking surveillance details.

Participants, including representatives of Human Rights Watch and Amnesty International, told reporters after the meeting that Snowden told them he wanted asylum in Russia since he could not fly out of the country without travel documents.

"Snowden is serious about obtaining political asylum in the Russian Federation," Vyacheslav Nikonov, a pro-Kremlin lawmaker who attended the meeting, said.

The US State Department said the meeting should not have taken place, and top US officials warned Moscow that offering asylum to Snowden would undercut its statements that it did not want the affair to harm relations with Washington.

White House spokesman Jay Carney said "Providing a propaganda platform for Mr Snowden runs counter to the Russian government's previous declarations of Russia's neutrality. It's also incompatible with Russian assurances that they do not want Mr Snowden to further damage US interests."

US President Barack Obama spoke to Russian President Vladimir Putin on the phone on Friday. The White House did not give further details about the phone conversation.

Meanwhile, Putin's spokesman repeated earlier conditions that Snowden should stop harming the interests of the US if he wanted asylum.

"We need to check this information, but as far as we know, he considers himself a defender of human rights and a campaigner for democratic ideals," spokesman Dmitry Peskov told Reuters news agency.

Those who attended the meeting included Sergei Nikitin, head of Amnesty International's Russia office, and Tatiana Lokshina, deputy head of the Russian office of Human Rights Watch.

Also taken into the meeting room were Russia's presidential human rights ombudsman Vladimir Lukin, prominent attorney Genri Reznik, and Nikonov.

'Unlawful campaign'

UN rights chief Navi Pillay said on Friday that there is need to protect whistleblowers, also from within intelligence agencies, who disclose human rights violations.

"Snowden's case has shown the need to protect persons disclosing information on matters that have implications for human rights, as well as the importance of ensuring respect for the right to privacy," Pillay said in a statement.

Snowden, 30, had not been seen in public since his arrival, and Russian officials have shown increasing impatience over his stay. But it has also become clear that Snowden has no clear route to a safe haven from Moscow.

Venezuela, Bolivia and Nicaragua have offered Snowden asylum, but he has not revealed his plans.

Washington, which seeks to arrest Snowden on charges of espionage in divulging details of US surveillance programmes, has revoked Snowden's passport and pressed nations not to take him in or help him travel.

"In recent weeks we have witnessed an unlawful campaign by officials in the US government to deny my right to seek and enjoy this asylum under Article 14 of the Universal Declaration of Human Rights," Snowden wrote earlier to the rights groups.

Meanwhile, leaders from Latin American bloc, Mercosur, meeting in Montevideo in Uruguay, were expected to send a tough message to Washington over allegations of US spying in the region and to defend their right to offer asylum to Snowden.