Hong Kong stocks retreated to a one-month low, as a slump in crude oil prices revived jitters about the global growth outlook and traders were closely monitoring the US presidential debate.

The Hang Seng Index fell 1.3% as of 10.53am local time, heading for the lowest since August 8. The Hang Seng Tech Index dropped 0.6%, and the Shanghai Composite Index retreated 0.8%.

Chinese oil producers led the decline on the market after prices tumbled by more than 4% overnight to an almost three-year low. PetroChina sank 5.1%, CNOOC dropped 5.1% and China Petroleum and Chemical Corp, also known as Sinopec, shed 5%. Chinese sportswear maker Li Ning slid 4.9% after Citigroup downgraded the stock to neutral from buy and reduced its price target by 27%.

The in-progress debate between US vice-president Kamala Harris and former president Donald Trump may offer stocks traders more clues on their respective policies on China, tariffs tax proposals, government budgets and new energy.

Flaircomm Microelectronics, a maker of auto electronics, jumped 65% to 65.7 yuan on its first day of trading in Shenzhen.