The Straits Times quoted a spokesman for the carrier as saying the suspension is due to "regulatory reasons" without elaborating further.
According to Singapore’s Chinese-language newspaper Lianhe Zaobao, the airline has not received approval from the Civil Aviation Administration of China to fly to the cities in summer and autumn 2024.
The flights were similarly suspended in 2023 and only resumed in November.
Singapore Airlines flies daily to Chengdu and thrice a week to Chongqing.
Singapore is the latest country in Southeast Asia to waive visa requirements for Chinese, with a mutual waiver taking effect on Feb. 9.