Victoria's workplace safety regulator is warning divers who filled their air tanks or cylinders at a dive shop in East Gippsland not to use them, after unsafe levels of carbon monoxide were found.

WorkSafe inspectors made the discovery after assessments at Cross Diving Services in Marlo, near Orbost.

The regulator said cylinders at the shop contained carbon monoxide levels of at least 150 parts per million, which is more than 30 times the maximum acceptable level.

The acceptable carbon monoxide level is 5 parts per million.

WorkSafe has issued notices banning the business from providing further cylinders or using an on-site compressor to fill them.

It said the owner of the business had been unable to provide complete records of who had had air tanks or cylinders filled at the shop.

The regulator has advised anyone who has had a cylinder or air tank filled at Cross Diving Services not to use it under any circumstances, and to contact WorkSafe on 1800 136 089.

The business was inspected following the death of a diver in Queenscliff in April which is subject to a coronial investigation.