The UK head of a Chinese-owned semiconductor company has said the decision to reverse its takeover of Britain’s largest chip plant is “bad news” for workers and pledged to do whatever it takes to fight the order. The business department late on Wednesday night ordered Nexperia to sell 86% of its shareholding in the company, formerly known as Newport Wafer Fab, which produces semiconductors in south Wales. The order, which cited national security concerns, would reverse a £63m takeover completed in July 2021. Toni Versluijs, Nexperia’s UK country manager, said the company “will do whatever is in our legal means to overturn the decision”, but acknowledged a failure to void the decision could threaten the jobs of about 550 staff at the site. “We are intending to overturn this decision. Then it will not threaten any jobs,” he said. If the order remains in place it “would be really bad news”. He added: “It would be really bad news for the people of Newport, it would be really bad news for semiconductors in the UK, it would be really bad news for taxpayers in the UK who will pay for the fallout from this.” Nexperia is based in the Netherlands but is owned by China’s Wingtech, a link to a geopolitical rival that had prompted concerns among prominent critics of Beijing in the Conservative party. Newport Wafer Fab, now known as Nexperia Newport, makes chips that are used for power management in electronic devices. Nexperia also operates a site in Stockport, near Manchester, which employs 1,000 people. Nexperia bought 14% of the factory in 2017 and bought the rest in July 2021 after it got into financial difficulties. It has said it was investing £80m in the site, with a focus on supplying chips to its automotive customers such as Jaguar Land Rover and Bosch. There is little precedent for how the company could successfully overturn the decision as it was made under powers introduced this year. Under the National Security and Investment Act, companies have 28 days to ask for a judicial review of the decision. The government said there were national security issues relating to technology and knowhow related to compound semiconductors, whose sales are growing more quickly than previous less efficient generations of the technology. The government also suggested a takeover could undermine the “south Wales cluster” of semiconductor companies, which aims to foster a complete supply chain in the UK. The order could open the way for the factory’s former owner, Drew Nelson, to mount a comeback deal. Nelson is believed to be keen to lead a consortium to take back control of the plant and run it as an open-access facility that other companies in the cluster could use to make their own chips. Versluijs said Nexperia had “offered far-reaching remedies to address these so called security concerns”, including putting a government representative on the board or management team of Nexperia Newport and pledging not to continue development of compound semiconductors. He also criticised the government’s handling of the process, which has been overseen by three different business secretaries in recent months – although nobody from the government visited the site, he added. The government delayed the final decision at the start of July, and released the decision later than expected on Wednesday. “Even the process itself already shows the UK is not open for business,” he said. “The mere length of the process already shows that things in the process need to be radically changed.” Versluijs said it was “very well possible” and “maybe even a likely” scenario that the government blocked the takeover because of the involvement of a Chinese company. He said he had had no contact with executives in China since the decision was announced, but said he had spoken to staff at the factory, adding: “The people are devastated. They really don’t understand this at all.”