Former US intelligence contractor Edward Snowden has legal right to become a Russian citizen after he was given leave to remain in Russia for another couple of years.

"Snowden's residency in Russia has just been extended by another couple of years," a Russian foreign ministry spokeswoman, Maria Zakharova, said in a post on Facebook.

The 33-year-old Mr Snowden is wanted in the United States to face trial on charges brought under the tough Espionage Act of 1917 after he leaked thousands of classified documents in 2013 revealing the vast US surveillance of private data put in place after the September 11, 2001 attacks.

His lawyer told RT the extension now gives Mr Snowden grounds to obtain Russian citizenship.

Last year he said he was not worried about the incoming Donald Trump administration stepping up efforts to arrest him and stood by his decision to leak the classified material.

“I don't care,” he said in November. “The reality here is that yes, Donald Trump has appointed a new director of the Central Intelligence Agency who uses me as a specific example to say that, look, dissidents should be put to death.

“But if I get hit by a bus, or a drone, or dropped off an airplane tomorrow, you know what? It doesn't actually matter that much to me, because I believe in the decisions that I've already made.”

The announcement came as President Barack Obama commuted the sentence of Chelsea Manning, the former army intelligence analyst who was convicted of leaking classified military documents to WikiLeaks.

The 29-year-old whistleblower, who was sentenced to 35-years in prison in August 2013, will now be released on 17 May of this year.