Former US intelligence contractor Edward Snowden, who exposed the scale of secret surveillance by the NSA, has sworn an oath of allegiance to Russia and received a Russian passport, TASS reports.

“Yes, he got (a passport), he took the oath,” Anatoly Kucherena, Snowden’s lawyer, told the state news agency.

Snowden, 39, did not immediately reply to a message seeking comment on the report.

“This is still a criminal investigative matter,” White House spokesman John Kirby told reporters on Friday, referring any questions about the report on Snowden to the US Department of Justice, which declined to comment.

US authorities have for years wanted Snowden returned to the United States to face a criminal trial on espionage charges.

President Vladimir Putin in September granted Russian citizenship to Snowden, who fled the United States after leaking secret files that revealed the extensive eavesdropping activities of the United States and its allies.

Defenders of Snowden hail him as a modern-day dissident for exposing the extent of US spying.

Opponents say he is a traitor who endangered lives by exposing the secret methods that Western spies use to listen in on hostile states and militants.

— AAP