An Australian man has pleaded guilty to filming and mocking police officers as they lay dying at a crash scene.

Richard Pusey, 42, admitted to the rare charge of outraging public decency as well as drug and other offences.

Pusey was in his car on a Melbourne freeway last year when he was pulled over by four officers for speeding.

While the officers were making his arrest, all four were struck by a passing lorry that had veered out of its lane.

Senior Constables Lynette Taylor and Kevin King and Constables Glen Humphris and Josh Prestney died at the scene.

Pusey had been standing a few metres away and avoided the crash, but afterwards pulled out his phone and began filming for over three minutes.

He stood over and taunted Senior Constable Taylor as she remained pinned under the lorry a court previously heard. Experts said she was most likely still alive at the time.

"There you go. Amazing, absolutely amazing," he said, according to vision from the constable's body-worn camera which was tendered to a court.

"All I wanted was to go home and have some sushi," he added, before using expletives to blame the officers for ruining his car.

He fled the scene on Melbourne's Eastern Freeway shortly after.

The lorry driver, Mohinder Singh Bajwa, has pleaded guilty to four charges of culpable driving causing death and will face another court hearing this week.

Pusey, a mortgage broker, was arrested at his home after the crash. He was initially charged with speeding, drug possession and reckless conduct offences.

However, police discovered Pusey's video and that he had shared it among friends.

His comments in the footage sparked public outrage, with Victoria's police minister condemning them as "completely sickening".

Local media reported that the offence of outraging public decency was rarely prosecuted in Australia.

Prosecutors in the case have referred to the 2007 case of Anthony Anderson in England, who was jailed for three years for urinating on a woman as she lay dying.

There is no maximum penalty for the charge in Australian law.

Pusey is due to face court again on 31 March.