Jan 5 (Reuters) - Winning International Group, the world's largest bauxite shipping firm, has left the International Aluminium Institute (IAI), the industry body said on Monday after updating its member list for the new year.

"Winning are no longer members of the IAI," the body's London secretariat said. The IAI website no longer lists Winning as a member.

Singapore-based Winning becomes the second company to leave the IAI in the past six months after China Hongqiao Group , the world's top private-sector aluminium producer, resigned in mid-2020.

Prior to that, IAI membership represented more than 60% of global output of aluminium metal, as well as raw materials bauxite and alumina.

It was not clear why Winning gave up membership in the IAI. A company spokesman declined to comment.

Winning has long shipped bauxite to Shandong-based Honqqiao and the two companies are partners in the SMB-Winning consortium that mines bauxite in Guinea.

Winning's exit leaves the IAI, which was set up in 1972 and works to expand the market for aluminium, with 25 members. These include state-owned Aluminum Corp of China, or Chinalco, Alcoa , Norsk Hydro, Rio Tinto and Rusal . (Reporting by Tom Daly and Pratima Desai; additional reporting by Mai Nguyen; Editing by Christian Schmollinger)