Ten Chinese spies have been charged in the US with hacking in to aviation firms in the UK, US, France, and Australia to steal trade secrets.

The US Justice Department unsealed an indictment accusing intelligence officers of taking sensitive data “to build the same or similar engine without incurring substantial research and development expenses".

It was the third round of charges brought by the US since late September against alleged Chinese spies targeting commercial secrets from aviation and aerospace companies that are often also American defence contractors.

The move came amid a shift in the US to a more assertive policy towards China on top of the escalating trade spat.

American leaders have repeatedly accused Beijing of overstepping its bounds, orchestrating a sophisticated economic and military campaign to bolster its influence, and getting ahead by cheating and stealing intellectual property from the West.

“This is just the beginning,” said John Demers, the assistant attorney general for national security. “Together with our federal partners, we will redouble our efforts to safeguard America’s ingenuity and investment.”

The officers – part of a regional unit of China’s Ministry of State Security, the agency responsible for domestic and foreign intelligence – stole turbofan engine plans and other confidential information from 13 companies, including two UK aerospace firms, which were not named in the indictment. Only one company’s name was revealed in court documents – Capstone Turbine, a gas turbine manufacturer in Los Angeles.