Some people who work in China’s central government said employees have been told to stop using iPhones. Others described a vaguer demand for officials to stop using foreign-brand phones and to use Chinese ones.

One message that circulated on WeChat, a ubiquitous Chinese social media service, cited a decision from a departmental leader that staff members were to be barred from using foreign-brand smartphones, laptops and other digital devices starting Sept. 7. The message said staff members were also prohibited from using these foreign-brand products for work in their own homes. Another message on WeChat said that staff members would be required to stop using iPhones by Oct. 1.

Discussion has appeared online for years about whether Chinese officials are barred from using iPhones, along with occasional denials of blanket bans. A Shanghai newspaper reported in 2014 that officials in that city were under pressure to abandon iPhones over security worries.

A researcher in a government-run research institute in Beijing, speaking on the condition of anonymity, said the drive to discourage the use of iPhones appeared to ripple from what Chinese officials and party newspapers have described as a strategy of “substitution for domestic products” in key technologies, which has picked up pace since last year. In a speech to senior officials in February, which was published in July, Xi Jinping, China’s leader, urged increased efforts to achieve self-sufficiency for China in scientific research and advanced technologies.

“We must go on the offensive for the national production of scientific and technological instruments and equipment, operating systems and basic software,” Mr. Xi said.

In recent weeks, China’s Minister of State Security has publicized cases that it said involved Chinese officials and other people in sensitive roles being recruited by U.S. intelligence agents. Earlier this year, Chinese government secrecy authorities warned about careless use of phones that could expose officials to hacking or leaking sensitive information.

Amy Chang Chien, Claire Fu and Li Yuan contributed reporting.