FILE PHOTO: Logos of BP are on display at a petrol station in Moscow, Russia, July 4, 2016. REUTERS/Sergei Karpukhin/File Photo

BEIJING (Reuters) - Oil major BP has started discharging about 1 million barrels of Angolan crude to a Chinese independent refiner, after holding the oil on water for two months due to slowing demand from private refiners, sources said on Thursday.

The Mercury Hope supertanker, chartered by BP and carrying about 2 million barrels of Angolan oil, offloaded part of the cargo in late May at Qingdao and has since been at sea in nearby waters, said the sources with knowledge of the matter.

The tanker began offloading the remaining part of its cargo to Shandong Qingyuan Group, a privately-controlled refiner based at Linzi, Shandong province, late on Wednesday.

The group, which operates a 104,000 barrels per day refiner, is a regular customer of BP which has expanded its crude oil marketing to Chinese independent refiners since 2015 after China opened crude oil imports to nearly 40 local plants.

Mercury Hope is one of four supertankers that BP brought to China carrying Angolan oil several months ago, but which have been held up or delayed off China’s east coast, unable to fully discharge oil due to slowing buying from private refiners.

BP did not respond to a request for comment. An official at Shandong Qingyuan’s management office said she was not in a position to comment.

In early July, BP discharged nearly 1 million barrels of oil from Texas, another of the four tankers, also to Qingyuan.

Qingyuan, one of China’s largest independently run lubricant producers, has received an annual crude import quota of 4.04 million tonnes for the last two years.

Shippers and oil traders said it was not unusual for producers like BP to ship cargoes before finding a buyer, but having cargoes orphaned for two months was less common.