Hong Kong stocks fell at the start of Thursday's trading session as investors digested the U.S. Treasury Department's latest bond buyback update, amid soaring oil prices driven by the ongoing Middle East crisis.

The Hang Seng Index shed 1.1%, or about 290 points, to 24,985.18. The Hang Seng China Enterprises Index lost 1.2%, or nearly 100 points, to 8,269.49.

Treasury yields climbed on Wednesday after the U.S. said it will buy back 10- to 20-year ​bonds worth up to $6 billion, which is now three times ⁠the size of its last long-term debt repurchase, and up from its August update of plans to double the buyback.

Meanwhile, the global oil benchmark breached the $100 mark as military hostilities between the U.S. and Iran intensified in a relentless effort to control the Strait of Hormuz.

Tehran said it is ready for a more intense conflict with the U.S., following the latest tit-for-tat exchange, in which five Iranian tankers were attacked and at least ten American-backed ships were targeted.