Police on Sunday appealed to witnesses to a fatal traffic accident overnight to come forward.

They said a 22-year-old motorcyclist and his 24-year-old female pillion passenger were travelling along Argyle Street towards Nathan Road just before 3am.

They said the motorcyclist collided with a taxi driven by a 27-year-old man when it was approaching the junction of Argyle Street and Nathan Road.

The motorcyclist and his passenger sustained serious multiple injuries and were taken to Kwong Wah Hospital, where they were certified dead just before four o'clock, police said.

The taxi driver and a 38-year old passenger suffered injuries to their limbs, and were also taken to Kwong Wah Hospital. An elderly male pedestrian was hit by fragments from the collision.