BEIJING/SINGAPORE, Sept 27 (Reuters) - Zhang Peng, head of the...

BEIJING/SINGAPORE, Sept 27 (Reuters) - Zhang Peng, head of the crude oil department in PetroChina's 0857.HK 601857.SS trading unit, has resigned after nearly 15 years with the firm, four sources with knowledge of the matter said on Thursday.

Zhang is expected to join Bank of China International's (BOCI) commodity team based in Hong Kong, said the sources, declining to be identified as they were not authorised to speak with media.

BOCI is a clearing member of key global commodity exchanges such as ICE and the London Metal Exchange (LME).

Zhang declined to comment. PetroChina and BOCI did not immediately respond to requests for comment.

Zhang's resignation from Chinaoil marks the second departure from a senior role at the state oil trading firm in about 18 months.

Zhang was promoted to his role at Chinaoil from a deputy position in early 2017, succeeding Li Chuang who resigned.

Li later joined Geneva-based Swiss commodities trader Mercuria as its Asia crude team leader.

Zhang, in his late 30s, worked in Chinaoil's crude oil department throughout his career with the company, including assignments in Houston and Calgary.