Fire damages Vic hospital's renal unit

A fire has damaged a part of a Melbourne hospital used by dialysis patients.

The Metropolitan Fire Brigade responded to an alarm at the Box Hill Hospital's renal unit early on Tuesday morning.

MFB fire services controller Ian Morris said the area was not being used at the time, but there was substantial smoke damage and crews took 40 to 50 minutes to extinguish the fire.

The cause is being investigated.

The hospital will make alternative arrangements for patients booked for Tuesday.