BEIJING • Beijing has accused the United States of "slander", after two Chinese nationals were indicted for seeking to steal coronavirus vaccine research and hacking hundreds of companies.

"The Chinese government is a staunch defender of cyber security, and has always opposed and cracked down on cyber attacks and cybercrime in all forms," said Chinese Foreign Ministry spokesman Wang Wenbin yesterday.

The US must "immediately stop its slander and smearing of China on cyber-security issues", Mr Wang told a regular news briefing.

The US Justice Department on Tuesday indicted Chinese nationals Li Xiaoyu and Dong Jiazhi over their role in what the agency called a decade-long cyber espionage campaign that has targeted defence contractors, Covid-19 researchers and hundreds of other victims worldwide.

The US authorities said the two Chinese men stole terabytes of weapons designs, drug information, software source code and personal data from targets that included Hong Kong protesters, the office of the Dalai Lama and a Chinese Christian non-profit organisation.

They were contractors for the Chinese government, rather than full-fledged spies, US officials said.

US Assistant Attorney-General for National Security John Demers said at a virtual press conference: "China has now taken its place, alongside Russia, Iran, and North Korea, in that shameful club of nations that provides safe haven for cyber criminals in exchange for those criminals being on call for the benefit of the state."

The indictment mostly did not name any companies or individual targets, but US attorney William Hyslop, who spoke alongside Mr Demers, cited "hundreds and hundreds of victims in the United States and worldwide".

Officials said the probe was triggered when the hackers broke into a network belonging to the Hanford Site, a decommissioned US nuclear complex in eastern Washington state, in 2015.

Li and Dong were "one of the most prolific groups of hackers we've investigated", said Federal Bureau of Investigation special agent Raymond Duda, who heads the agency's Seattle field office.

A July 7 indictment made public on Tuesday alleges that Li and Dong were contractors for China's Ministry of State Security, a comparable agency to the US' Central Intelligence Agency.

As early as Jan 27, as the coronavirus outbreak was coming into focus, the hackers were trying to steal Covid-19 vaccine research of an unidentified Massachusetts biotechnology firm, the indictment said. It is unclear whether anything was stolen.

AGENCE FRANCE-PRESSE, REUTERS