China called a US claim that it had facilitated the departure of former security contractor Edward Snowden from Hong Kong "groundless" on Tuesday, after Washington said Beijing had chosen to release him.

"It is unreasonable for the US to question Hong Kong's handling of affairs in accordance with law, and the accusation against the Chinese central government is groundless," foreign ministry spokeswoman Hua Chunying told a regular press briefing in Beijing, adding: "China cannot accept that."

Her remarks came after White House spokesman Jay Carney lashed out at Beijing for letting Snowden go, despite a US arrest warrant.

"This was a deliberate choice by the government to release a fugitive despite a valid arrest warrant, and that decision unquestionably has a negative impact on the US-China relationship," he said.

Snowden left Hong Kong for Moscow on Sunday, infuriating Washington which had requested his arrest and extradition on espionage charges.

Beijing maintains influence over Hong Kong's government, and analysts speculated that it intervened in Snowden's case because of its potential to create a drawn-out legal saga that would strain relations between the US and China.

China's foreign ministry has repeatedly said that Hong Kong handled the case according to local laws.

His shock departure has disappointed rights advocates in the southern Chinese city, after he initially said he would stay and fight extradition in what would have been an important test for Hong Kong's judicial independence.

Snowden is said to be seeking asylum in Ecuador, but his exact whereabouts are currently unknown, after he failed to board a flight booked from Moscow to Cuba in his name on Monday.