A handful of Chinese ministries have told employees to stop using Apple’s iPhones at work, citing national security risks amid heightened geopolitical tensions with the United States, according to several people familiar with the matter.

The orders were handed down in August to employees at ministries whose portfolios are focused on investment, trade and international affairs, according to five separate sources with knowledge of the situation.

The measures were understood to be aimed at eliminating perceived national security risks from using telecommunication devices made by a US company, sources said.