China has launched an operation to clean up a large oil spill in the Yellow Sea after two oil pipelines exploded in the port city of Dalian late on Friday.

Oil-skimming vessels and other ships have been deployed to remove the slick, which is reported to cover 50 sq km (19 sq miles).

Fires started by the blasts late on Friday burned throughout the weekend. No deaths or injuries were reported.

Around 2,000 firefighters battled the flames, which broke out after a pipe carrying oil from a tanker to a storage tank blew up, causing another nearby pipeline to explode.

The authorities have closed the port, which regularly receives foreign vessels carrying crude oil, and is also a main export point for petrol and diesel.

The pipelines belong to the China National Petroleum Corporation, Asia's largest oil and gas producer by volume.

Officials said the flames gave off gas containing sulphur and an aromatic hydrocarbon - but that they were not fatally toxic.