The massive US global surveillance program revealed by a former CIA whistle-blower in Hong Kong is certain to stain Washington's overseas image and test developing Sino-US ties, analysts said.

Li Haidong, a researcher of American studies at China Foreign Affairs University, said the United States is now stuck in the awkward position of having to explain itself to its citizens and the world following the exposure of Washington's vast Internet snooping program.

"For months, Washington has been accusing China of cyberespionage, but it turns out that the biggest threat to the pursuit of individual freedom and privacy in the US is the unbridled power of the government," Li said.