Ships seeking bunker fuel at Zhoushan, China, are facing significantly longer waiting times as tightening fuel supplies disrupt operations at China's leading bunkering hub, according to Bloomberg.

The news agency reported that vessels calling at the port south of Shanghai are encountering delays of around one to two weeks for refuelling.

Under normal conditions, waiting times are typically one to two days.

Bloomberg attributed the longer queues to supply constraints linked to the conflict in the Middle East, which has limited crude oil imports.

The report also said Chinese refiners have shifted production towards gasoline and diesel, reducing output of residual fuel oil used in bunker fuel.

As supplies have tightened, prices for very low-sulphur fuel oil (VLSFO) in Zhoushan have risen. Spot prices were close to their highest level since March and stood more than 25% above those in Singapore.

This is coupled with a decline in low-sulphur fuel oil production by Chinese state-owned refiners. Output totalled 1.12 million tonnes in August, down 13% from July, contributing to the current shortage.

According to the report, pressure in the fuel oil market is expected to ease in early October.

Analysts cited by the news agency said this would be supported in part by a seasonal reduction in demand during China's week-long national holiday, while bunkering activity at several Chinese ports is also expected to slow over the period.

Zhoushan (CNZOS), located south of Shanghai within the Ningbo-Zhoushan port complex, is China's largest bunkering hub and a major refuelling location for international vessels. Chinese authorities have sought to develop the port into a regional alternative to Singapore by expanding bonded fuel supply services and refining capacity.