Apple fell more than 3% and was on track for its worst two-day decline since November after media reports said Beijing has told employees at some central government agencies in recent weeks to stop using their Apple mobiles at work.

Several Wall Street analysts said the curbs show that even a company with a good relationship with the Chinese government and a large presence in the world's second-largest economy was not immune to rising tensions between the two nations.

CONSTRAINING A WESTERN COMPANY

Apple supplier Qualcomm, one of the U.S. companies with the largest China presence, tumbled nearly 7% to lead losses among major tech firms.

The wider ban is not surprising and highlights efforts to limit a Western company's market access to China, said U.S. Representative Mike Gallagher, the chairman of the House panel on China.

"This is textbook Chinese Communist Party behavior - promote PRC (People's Republic of China) national champions in telecommunications, and slowly squeeze Western companies' market access," Gallagher, a Republican, told Reuters.

Sino-U.S. friction has risen in recent months as Washington tries to restrict China's access to key technologies including cutting-edge chips, and Beijing looks to reduce its reliance on American tech. China has curbed shipments from prominent U.S. firms including planemaker Boeing and memory chipmaker Micron.

"This announcement seems to have just refocused investors that the relationship between the U.S. and China is a big risk to current equity prices, particularly in technology," said Rick Meckler, partner at Cherry Lane Investments.

Other suppliers of the iPhone maker including Broadcom , Skyworks Solutions and Texas Instruments were also lower, falling between 2% and 7.3%. The drop in the technology sector weighed on the three main U.S. stock indexes, particularly the tech-heavy Nasdaq Composite, which lost 1.1% in afternoon trading.

iPHONE SLOWDOWN

China has been a bright spot for Apple in an otherwise tough period for iPhone sales.

"China is a crucial market for Apple, not just because it's a super-important manufacturing hub, but because the country is an increasingly important source of revenues," said Susannah Streeter, head of money and markets at Hargreaves Lansdown.

Apple gets nearly a fifth of its revenue from the country.

"Already rivals are closing the gap in high-end smartphone sales, and if the situation were to escalate this could potentially allow competitors to have a greater chance of stealing Apple's crown," Streeter said.

China's Huawei last week launched its new Mate 60 Pro smartphone, which is powered by an advanced chip made by Chinese contract chipmaker SMIC and marks a breakthrough for the duo hit by U.S. sanctions.

Those sanctions cut Huawei's access to chipmaking tools essential for producing the most advanced handset models, hammering the company's business and allowing Apple to take some market share from the national favorite in China.

"If Huawei has the capability to supply and scale its home-grown Kirin 9000S (chips), we see the Mate series phone as an opportunity for Huawei to increase its shipments and regain its market share," analysts at BofA Global Research said.

Apple could, however, see a demand boost after an event next week where it is expected to unveil its iPhone 15 line-up, as well as new smartwatches.

• China Bans Gov't Officials From Using iPhones