US President Barack Obama said today he would not "scramble jets" to intercept any flights carrying fugitive leaker Edward Snowden and scoffed at spending political capital to win him back from Russia.

Obama, questioned in Africa on the latest twists of the international spy drama involving Snowden and his exposure of US phone and Internet surveillance programmes, did however admit he was worried about what other secrets might leak.

His comments came as Snowden remained in Russia, where he fled from Hong Kong, stuck in the transit zone of a Moscow airport, apparently unable to travel on to possible asylum in Ecuador after Washington cancelled his passport.

Obama, who has been embarrassed by the refusal of first China and then Russia to expel Snowden, insisted the real damage to the United States lay not in international humiliation, but in the exposure of key spying programmes.

But he ruled out military action should Snowden eventually manage to get on a flight out of Russia.

"No, I am not going to be scrambling jets to get a 29-year-old hacker," Obama said, at a media conference in Senegal.

The US leader also said that he had not called the Chinese or Russian presidents to plead with them to hand Snowden over, because his government was using regular legal channels for an extradition case.

"I have not called President Xi (Jinping) personally or President (Vladimir) Putin personally. The reason is, number one, I shouldn't have to. This is something that routinely is dealt between law enforcement officials in various countries."

Obama said that the US and China relationships were broad and ranged over many issues and that he would not get down to "wheeling and dealing" with Russia and China over one extradition case.