Chinese researchers working in hi-tech sectors were warned not to take any unnecessary trips to the US.

Staff at a research agency were also told that if they did have to travel to the US, they should remove any sensitive information from their mobile phones and laptops.

Tensions between Beijing and Washington continued to escalate after the arrest of Huawei Technologies chief financial officer Sabrina Meng Wanzhou in Canada.

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.

Read more: Trump says he would intercede with Huawei's Meng Wanzhou case if it's good for trade, security, according to report

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.

Some researchers have also had their computers and mobile phones subjected to checks by US customs officers, two other sources said.

Observers say they are concerned that it will be more difficult to de-escalate tensions between Beijing and Washington — and the distrust and "information deficit" could worsen — with fewer academic exchanges between the two sides.

Chinese tourists take photographs of themselves outside of the New York Stock Exchange Lucas Jackson/Reuters An academic who frequently travels across the Pacific feared changing sentiment in the United States, from engagement to disengagement with Beijing, could lead to a US strategy of full-scale containment of China.

Read more: A former Canadian diplomat was detained in Beijing after China warned of consequences for the arrest of Huawei's CFO

At the request of the US authorities, Huawei executive Meng was arrested on December 1 in Vancouver and was released on bail on Tuesday. She could be extradited to the US to face fraud charges relating to alleged violations of US and EU sanctions on Iran.

Meng's arrest has added to wariness among businesspeople in both countries. A Chinese executive whose operation covers Southeast Asia and Africa said the case had made him, and others like him, nervous about travelling abroad.

"The long-arm jurisdiction in the US will force us to stay in China if Meng is extradited to the US," the businessman said, speaking on condition of anonymity because the issue is highly sensitive.

On Friday, US technology giant Cisco sent an email to staff in the United States asking them to cut non-essential travel to China, amid growing anxiety that American executives could be targeted by Beijing in retaliation for Meng's arrest.

Some US-based Cisco employees said they had received the email, saying the restriction would take effect immediately. The company admitted the email existed but said it was "sent in error to some employees."

Read more: An arrest, a debutante ball, and 3 marriages: Inside the lives of the super rich Huawei dynasty

And on Monday, less than two weeks after Meng's arrest, a Canadian former diplomat was detained in China by state security. China has so far declined to reveal the whereabouts of Michael Kovrig, a senior adviser with the International Crisis Group who was a diplomat in Beijing before he joined the NGO.

The following day, Reuters cited two sources as saying that the US was considering issuing a warning to US citizens about travelling to China in the wake of Huawei case.

Meanwhile, US President Donald Trump was reportedly advised by his aides to ban Chinese from studying in the US, amid concerns over China's influence in the country.

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.

Trump has labelled China a strategic competitor and criticised Beijing for industrial policies such as "Made in China 2025", which aims to move the country up the manufacturing value chain.

That led to the US in June restricting visas for Chinese graduates in robotics, aviation, and advanced manufacturing from a maximum of five years to 12 months.