Hong Kong's social unrest may be prompting globe-trotting millionaires to locate to Singapore instead, according to a wealth-tracking report out on Tuesday.

The two cities are locked in a struggle for supremacy as Asia-Pacific financial hubs, attracting financial professionals and investors away from London and New York.

"Though Hong Kong has a much higher millionaire population than Singapore (193,000 against Singapore's 154,000), recent events such as the Umbrella Revolution may have turned migratory high-net-worth individuals (HNWIs) away from the city," Oliver Williams, head of WealthInsight, said in a report from the research company.

Approximately 1 in 35 Singaporeans are currently millionaires, according to WealthInsight. The city-state's HNWI population is seen growing by 18.3 percent to reach 188,000 by 2020, making around 1 in 30 Singaporeans millionaires.

By comparison, the number of millionaires in Hong Kong is seen growing by 15.6 percent over the next five years.