TAIPEI -- Taiwan's information technology sector, a closely watched bellwether of the global market, showed a 9.7% year-on-year increase in revenues for September. But signs of a slowdown are emerging as trade tensions between Washington and Beijing escalate.

At 1.22 trillion New Taiwan dollars ($39.5 billion), combined revenues at 19 key Taiwanese IT companies hit a record for a September. Growth continued for a seventh straight month.

Makers of iPhones and their parts posted notable upswings. Hon Hai Precision Industry, or Foxconn, reported a 29.6% jump in revenue. Taiwan Semiconductor Manufacturing Co., which produces chips for the Apple handsets, logged 7.1% growth.

Apple announced the high-end iPhone XS and other new offerings in September. The bulk of the handsets are assembled by Foxconn in China for shipment around the world.

While big-name companies bolstered by iPhone demand led overall growth in the Taiwanese IT sector, 10 of the 19 players logged revenue declines for September.

At smartphone lens maker Largan Precision, revenue rose just 1.3%.

Most Largan customers are revising down orders, CEO Adam Lin recently reported. Amid the ongoing China-U.S. trade war, smartphone makers are said to be cutting back on capital investments.

Taiwan serves as a production hub for technology equipment and parts for such companies as Apple and Huawei Technologies. Investors on and off the island monitor the industry to gain insight into global trends.