Three men have been arrested over an attack last month on Equal Opportunities Commission board member Qamar Zaman Minhas, police said.
The three suspects, aged from 29 to 36 and of South Asian origin, were detained in Yuen Long and Hung Hom on Friday and Saturday and charged with wounding.
The men are all Hong Kong residents, detective chief inspector for Yau Tsim district Yolanda Yu Hoi-kwan said, but another two suspects were still at large, both of them asylum seekers from South Asia.
"There might be more arrests in the future," Yu said.
Minhas, 43, who is also president of the Pakistan Association of Hong Kong, was stabbed in a mysterious attack shortly after 2pm on January 10 when walking with a friend outside Burlington House on Nathan Road in Tsim Sha Tsui.
The pair ran into a shoe shop to seek help after the attack.
Minhas suffered a 40-centimetre wound to his back and was taken to Queen Elizabeth Hospital in Yau Ma Tei for treatment.
It is believed the three suspects all knew the victim.
Police said further investigation was needed to determine if the suspects were involved with triads and their motives for the attack.
Police dogs were taken to Chungking Mansions in Tsim Sha Tsui yesterday, where a snack stall and a mobile phone shop - both owned by one of the suspects, a 33-year-old - were searched for half an hour.
A source said that one suspect had once taken part in an election at a local association for Pakistanis, but it was unclear if this was the association of which Minhas is president.
Officers also searched a flat in Tin Shui Wai's Tin Yuet Estate yesterday, where one of the suspects lived.
The five suspects were identified from surveillance camera footage and intelligence collected by detectives, Yu said.
The United Muslim Association of Hong Kong wrote to Chief Executive Leung Chun-ying last month demanding police investigate the attack, which they said had "damaged the reputation of a peaceful city".
The association requested Leung take "immediate and serious action" to provide "comfort and safety" to the public, and also called on him to monitor the case personally.