A British artificial intelligence firm was allegedly targeted by two Chinese men as part of a hacking campaign lasting more than 10 years, the United States has claimed.

Li Xiaoyu and Dong Jiazhi are accused of hacking into hundreds of computer systems of companies, governments and organisations across the world, stealing “hundreds of millions of dollars’ worth of trade secrets, intellectual property and other valuable business information”.

American prosecutors claim the pair – who met at university – operated from China both for their own gain and with the assistance of and for the benefit of the Chinese government’s Ministry of State Security.

The unnamed company is referred to as a “UK artificial intelligence and cancer research firm” which is believed to have had its network compromised in April this year.

It is listed in court documents among 25 known cases, largely from the US but also including targets in Australia, Belgium, Germany, Japan, Lithuania, the Netherlands, Spain, South Korea, Sweden.

Victims range across various industries, from pharmaceuticals and defence to educational and gaming software.

More recently, the defendants probed for vulnerabilities in computer networks of companies developing coronavirus vaccines, testing technology, and treatments, the US Department of Justice said.

According to the indictment, one of tactics used by the duo centred on software and web vulnerabilities, some of which were newly announced, meaning companies would not have enough time to install a fix.

The charges come amid heightened tensions between China and the West, with the UK recently suspending an extradition treaty with Hong Kong, as well as extending an arms embargo to the region and imposing a ban on Chinese firm Huawei’s 5G equipment.

John C Demers, Assistant Attorney General for National Security in the US, said: “China has now taken its place, alongside Russia, Iran and North Korea, in that shameful club of nations that provide a safe haven for cyber criminals in exchange for those criminals being ‘on call’ to work for the benefit of the state, here to feed the Chinese Communist Party’s insatiable hunger for American and other non-Chinese companies’ hard-earned intellectual property, including Covid-19 research.”