A leading collector of contemporary Chinese art has pledged more than 1,400 works collectively valued at about $165-million to a future Hong Kong museum, according to The New York Times and Reuters.

The donation by Uli Sigg, and businessman and former Swiss ambassador to China, to the planned M+ museum lends a significant hand to Hong Kong’s ambitious and long-gestating effort to develop a world-class arts district.

The trove of early-1990s includes 26 pieces by the dissident artist Ai Weiwei, who was detained for several months last year by China’s government. Mr. Sigg declined to comment on Mr. Ai’s case but said that in deciding where to donate the works, he rejected options on the Chinese mainland because “conditions are not such that art could be shown without limitations.”

The donation is the first major gift for M+, which is slated to open in 2017. The museum also purchased a collection of 1970s and ’80s works from Mr. Sigg for $177-million.