Chinese researchers working in sensitive hi-tech sectors have been warned not to take any unnecessary trips to the United States, a source says, as unease grows in the business community following the arrest of a tech executive in Canada.

Staff at a research agency were also told in an internal memo that if they did have to travel to the US, they should remove any sensitive information from their mobile phones and laptops, according to the source who was speaking on condition of anonymity.

Despite the world’s two biggest economies agreeing to a 90-day truce in the trade war, tensions between Beijing and Washington have continued to escalate over technology and security. And the arrest of Huawei Technologies chief financial officer Sabrina Meng Wanzhou in Canada has further strained ties.

The South China Morning Post reported last month that the US embassy in Beijing had revoked 10-year multiple-entry visas issued to some researchers specialising in China-US relations at government-backed institutions without explanation amid tightened visa scrutiny.

Washington has also accused China of cyber and intellectual property theft, forced technology transfers and “unfair trade practices” that hurt the US economy, and it has stepped up screening of Chinese with access to American hi-tech sectors.