Whistleblowers have not yet come forward to report IMO 2020 infractions, according to the head of the US Coast Guard.

Speaking to TradeWinds at the Coast Guard Academy on Wednesday, Commandant Admiral Karl Schultz said he had not heard of anyone coming forward.

"I am unaware of any IMO reduced sulphur fuel whistleblower cases to date," he said.

"I have not heard of any of these cases [making their way] way here to the Coast Guard or [the Department of Justice]."