A 53-year-old man was arrested on suspicion of common assault after allegedly attacking a wheelchair user on a bus on Tuesday morning.

Police said the 67-year-old man boarded a bus on a wheelchair at Tin Ma Court bus stop in Wong Tai Sin at around 11.40am, and asked the driver to help fasten his seatbelt.

It's understood that the suspect became impatient and complained about the delay, and allegedly struck the wheelchair user on the head with a mobile phone.

The victim was taken to Queen Elizabeth Hospital for treatment.

Police have detained the suspect for further investigation.