ASML Holding , the leading maker of lithography machines for producing semiconductors , said a former employee in China stole data about its proprietary technology and export controls may have been violated as a result. Based in the Netherlands, ASML said it reported the data breach to authorities and initiated an internal review. It also implemented remedial measures after the incident. This marks the second time in as many years that ASML has levelled charges against Chinese entities. A year ago, ASML accused a Beijing-based firm of potentially stealing its trade secrets. It is unclear in the latest disclosure if the data stolen could be employed in developing lithography systems. But the company, which is restricted from selling its most-advanced lithography machines to China, said in its annual report that the theft, which it is still investigating, is not material to its business. The Dutch company is one of the key players in the rising conflict between the US and China over access to advanced chip-making machines. Washington implemented sweeping restrictions on American companies’ ability to export chip-making equipment in October last year, and has since persuaded the Netherlands and Japan to join the effort . ASML chief executive Peter Wennink has resisted some of the restrictions on his company’s ability to sell into China. He has warned that China will ultimately develop its own domestic alternatives if it cannot buy from the West. ASML is considered the leading developer of cutting-edge chip-making equipment that giants from Intel Corp to Taiwan Semiconductor Manufacturing Co employ to make their most advanced integrated circuits. Under pressure from the US, the Dutch government imposed curbs that have restricted ASML from selling its most advanced machines to China since 2019. China faces more US pressure on semiconductor front in 2023 ASML, meanwhile, said it does not expect new restrictions on exports to China to affect its 2023 earnings, according to its annual report on Wednesday. In a foreword to the report, Wennink said the company understood that the governments of the US, Japan and the Netherlands reached some agreement in late January, but no details have been disclosed publicly and any new restrictions would take months to draw up and enact. “We understand that steps have been taken that would cover advanced lithography tools as well as other types of equipment,” he said. “We do not expect these measures to have a material effect on our expectations for 2023.” ASML last month forecast a 25 per cent rise in sales for 2023, with sales to China steady at about 2.2 billion euros (US$2.36 billion), or 14 per cent of its total annual revenue.