Russian President Vladimir Putin says US intelligence leaker Edward Snowden, who received asylum in Russia, is a "strange guy" who condemned himself to a difficult fate.

"You know, I sometimes thought about him, he is a strange guy," ex-KGB spy Putin said on Wednesday in an interview with state-run Channel One television.

"I do not have the faintest idea about what he will do next": Vladimir Putin doesn't know what's in store for NSA whistleblower Edward Snowden. Credit:Reuters

"How is he going to build his life? In effect, he condemned himself to a rather difficult life. I do not have the faintest idea about what he will do next," Putin said.

The case has intensified strains between Russia and America and prompted US President Barack Obama to cancel a visit to Moscow for a bilateral summit ahead of the G20 summit in Saint Petersburg this week.