A man in his 70s has been arrested as part of a probe under the Official Secrets Act, police said on Thursday, amid reports he was a former Rolls-Royce engineer suspected of divulging secrets about Britain's new stealth fighter to China. Scotland Yard said the man was arrested on Tuesday afternoon and taken to a police station in Derbyshire before being released under investigation. A search at an address in Derbyshire was ongoing while a search warrant was also executed at an office address in the West Midlands. The man was named by the Sun as Bryn Jones, a former chief combustion technologist, who it said had been detained in connection with efforts by China to obtain classified information about Britain's new £100million RAF stealth fighter jet. The 73-year-old former Rolls-Royce employee was reportedly held after MI5 received information that classified details were passed to Beijing. Factfile | F-35 Lightning II fighter He was detained in an “ultra-discreet” swoop by officers from Scotland Yard’s SO15 counter-terrorism command at his home on Tuesday, it was reported. Mr Jones, who describes himself as a “visiting professor” in “gas turbine combustion” at the Aeronautical University of Xian, central China, denies any wrongdoing, the newspaper reported. The investigation reportedly centres on information about the F-35 Lightning II jet, which arrived in Britain last week. Britain has committed to buying 138 F-35 fighter aircraft and has so far bought 48 at a cost of £9.1 billion. The F-35 programme is the world’s largest defence development, worth over $1.3trillion. UK industry provides 15 per cent of each of the 3,000 aircraft currently on the order books and at peak production 25,000 British jobs will be supported throughout the supply chain.