The Buildings Department said an incident on Tuesday involving a piece of concrete hitting a double-decker bus in Mong Kok may be linked to work being carried out by a contractor on the building's exterior wall.

The chunk of concrete fell from Sun Hing Building on Nathan Road and hit the bus at around 9.20am.

Officers said that the concrete block, measuring approximately 25cm by 25cm, fell from the building's exterior wall.

No one was injured.

A 47-year-old building contractor was arrested in connection with the case.

A 50cm by 30cm piece of concrete fell from the same building two weeks ago.