The collision involving the anchored Liberia-flagged tanker A Symphony and the bulk vessel Sea Justice took place at 0850 local time (0050 GMT), A Symphony's manager Goodwood Ship Management said in an e-mail.

"The force of the impact on the forward port side caused a breach in cargo tanks and ballast tanks, with a quantity of oil lost into the ocean," Goodwood said, adding all of the crew had been accounted for and there were no injuries.

Oil tanker 'A Symphony' leaking oil off Qingdao, China after collision

It was not immediately possible to contact the owner of the Sea Justice and the extent of the spill was also unclear as operations to contain it were hindered by the fog.

"The oil spill came after a clash between two vessels," an official for China's Shandong Maritime Safety Administration told Reuters on condition of anonymity, confirming that no one was injured.

Heavy fog, which has hampered navigation off the Qingdao coast since Monday, led to poor visibility at the time of the collision, Goodwood said.

It said emergency procedures on board the vessel were instigated to limit any spill and the vessel's oil spill response team was mobilised.

The incident was reported to local authorities and a clean up operation has begun, although it was hindered by the port's closure because of "zero visibility," Goodwood said.

The Shandong Maritime Safety Administration has instructed other ships to stay at least 10 nautical miles from the A Symphony, but did not provide details on how much oil has leaked.

Bulk carrier collides with oil tanker at Qingdao Bulk carrier collides with oil tanker at Qingdao https://graphics.reuters.com/CHINA-OIL/SPILL/qzjvqzlbapx/chart.png

Oil tanker safety has improved in recent decades - partly due to the introduction of double-hulled ships - and major spills are rare, although there are still risks with the transport of oil by sea, which has the potential to cause major environmental damage.

The A Symphony, a Suezmax tanker, was last seen near the Qingdao port, live shipping data on Refinitiv Eikon showed.

The tanker called at Linggi International Transhipment Hub, near Malacca in peninsular Malaysia, earlier this month, where it fully loaded with oil and set sail for China, the data showed.

Contacted by Reuters, an executive at Run Cheng International Resource (HK) Co said the company owned the 150,000-tonne cargo of bitumen blend on board A Symphony.

Bitumen, a mixture of hydrocarbons from residue in refining, is used for road surfacing and roofing. However, shipping sources said bitumen is typically moved in smaller vessels with specialised heating rather than suezmaxes.

The 272 metre-long and 46 metre-wide oil tanker was sold in May 2019 to its new owners Symphony Shipholding SA and NGM Energy, Equasis data showed.

Symphony Shipholding SA and NGM Energy could not be immediately reached for comment.

(Reporting by Muyu Xu in Beijing, Koustav Samanta, Jessica Jaganathan, Shu Zhang, Roslan Khasawneh and Gavin Maguire in Singapore, Jonathan Saul in London; Writing by Florence Tan, Editing by Louise Heavens and Barbara Lewis)

By Koustav Samanta, Muyu Xu and Jessica Jaganathan