HONG KONG, April 29 (Reuters) - Citigroup's former Asia CEO Robert Morse said on Wednesday he has launched a financial services firm with US$1 billion ($1.5 billion) under management, together with two former colleagues.

Former HSBC Asia investment banking head Huan Guocang is the co-chairman of the firm, Primus Financial Holdings, which plans to build a financial group with financial advisory, wealth management and private equity services, Morse said. He is also the co-chairman of the firm.

Wing-Fai Ng, currently managing partner of Primus Pacific Partners, will be co-CEO of the new firm with Morse.

Morse told Reuters that the US$1 billion under management came from a single investor.

Morse, who had overseen Citigroup's rapid expansion and investment in China in the past decade, left the U.S. bank in August 2008 after 23 years at what was once the world's biggest financial services provider.

His formal title was chief executive of Citigroup's Asia Pacific institutional clients group. Before moving to the Asia post in 2004, Morse had been head of global investment banking at Citigroup. He was also chief executive of Salomon Smith Barney's Asia-Pacific operations in 1997 and 1998.

(Reporting by George Chen and Michael Flaherty; Editing by Ken Wills)