The National Security Agency (NSA) logo is shown on a computer screen inside the NSA in Fort Meade, Maryland.

Chinese state media on Wednesday criticized the United States for hindering efforts to stop global cyber threats in the wake of the WannaCry "ransomware" attack that has infected more than 300,000 computers worldwide in recent days.

The U.S. National Security Agency (NSA) should shoulder some blame for the attack, which targets vulnerabilities in Microsoft Corp systems and has infected some 30,000 Chinese organisations as of Saturday, the China Daily said.

"Concerted efforts to tackle cyber crimes have been hindered by the actions of the United States," it said, adding that Washington had "no credible evidence" to support bans on Chinese tech firms in the United States following the attack.

The malware attack, which began on Friday and has been linked by some researchers to previous hits by a North Korean-run hacking operation, leveraged a tool built by the NSA that leaked online in April, Microsoft says.

It comes as China prepares to enforce a wide-reaching cyber security law that U.S. business groups say will threaten the operations of foreign firms in China with strict local data storage laws and stringent surveillance requirements.

China's cyber authorities have repeatedly pushed for what they call a more "equitable" balance in global cyber governance, criticizing U.S. dominance.