Three explosions at Sydney restaurant

Three gas explosions inside a Chinese restaurant in Sydney has left two kitchen workers with serious burns.

A fire broke out at the Waterloo restaurant after 6.30pm on Saturday with NSW Fire and Rescue saying a leaking gas cylinder was to blame.

The LPG cylinder exploded a second time as crews arrived on the scene, and then a third time when the crews were inside the restaurant.

"The LPG cylinders were leaking and that then found an ignition source inside the kitchen ... that was the cause of the three explosions," NSW Fire Inspector Craig Wright told the Nine Network.

The explosions prompted a warning from NSW Fire and Rescue.

"What we ask is that under no circumstances LPG cylinders are used for any purpose inside a building," Mr Wright said.

Two male staff members aged 29 and 35 suffered serious burns to their face and arms.