An oil pipeline explosion has killed 22 people in the coastal city of Qingdao, according to state media.

Xinhua, the Chinese state news agency, reports that the explosion occurred while workers were trying to fix the Huangwei pipeline in the Huangdao district at around 10am local time (2pmGMT) after a leak occurred early in the morning.

Sinopec, China's largest oil refiner, is thought to own the pipeline and the explosion took place near a petrochemical plant, although Xinhau reports that the facility was not immediately endangered.

Over 100 fire fighters were involved in putting out the fire which was put out by 1pm local time (5pm GMT).

Photographs began to circulate on Sina Weibo, the Chinese social networking site, with pictures posted to Sinopec's microblogging service showing roads turned into rubble and black smoke rising from the blast.

A two-metre-wide oil belt could be seen in waters around the scene of the explosion, the Xinhua report claimed.

The pipeline, 176km long, connects oil depots in Huangdao to Weifang city, which holds a number of petrochemical plants.

Local authorities have ruled out terrorism as a cause for the blast but the incident remains under investigation.