HONG KONG, Jan 8 (Reuters) - Thomas Kwan, chief executive of Harvest Global Investment, the Hong Kong unit of China's 1.5 trillion yuan ($209.5 billion) asset manager Harvest Fund Management has stepped down, according to the former business chief and two sources familiar with the matter.

Kwan told Reuters on Monday that he will remain as a senior advisor to the parent group and will start his own advisory and private equity business focused on the Middle East.

He will be replaced by Han Tongli, a portfolio manager at Harvest, the two sources said, asking not to be named as they are not authorised to speak to media.

Harvest did not reply to a Reuters' request for comment.

Kwan is one of the longest-serving chief executives at a Chinese asset manager in Hong Kong, having acted as Harvest's Hong Kong CEO since 2015.

Harvest Global is an active, fundamental research driven manager with $207 billion asset under management, according to its website. ($1 = 7.1591 Chinese yuan renminbi) (Reporting by Xie Yu and Selena Li, Editing by Louise Heavens)