A planned museum dedicated to China's brutal crackdown on the Tiananmen Square pro-democracy protests has run into a legal challenge in Hong Kong that some say is motivated by Communist Party interests ahead of the event's 25th anniversary.

Hong Kong, a former British colony that reverted to Chinese rule in 1997, remains a freewheeling capitalist hub whose annual candlelight vigils every June 4 set it apart from mainland China, where all public commemorations of the anniversary are banned.

Discussion of the Tiananmen Square crackdown is still taboo in China, whose leaders ordered troops to open fire on demonstrators on June 3 and 4, 1989, and sent in tanks to crush a student-led campaign movement, killing hundreds.