The construction company responsible for spilling dirt across the Sydney Harbour Bridge has been slapped with an additional 28 road defects on its fleet.

The rear door of the Moits truck trailer became unlatched while driving across the bridge on January 22, spilling 20 tonnes of landfill over 3km.

The spill caused significant traffic delays in the lead up to the Australia Day long weekend period.

NSW Police inspected 39 other Moits units on Wednesday and issued 28 defects for substandard brakes, suspension and linking arms.

“Of concern to us and the task force is the loading practices of this particular company,” Acting Assistant Commissioner Stuart Smith said.

“Obviously the rear gate of the heavy vehicle on the Sydney Harbour Bridge was defective.”

Mr Smith said Moits was co-operating with police to resolve the issue but may be subject to future audits.

In a statement, Moits apologised for the accident.

“Moits have been in business for over 33 years and have a great track record,” the statement said.

“(The) majority of people understood this was an accident and we thank them for their support of kind words on social media.”

Moits chief executive Joe Vinci said the truck went over a bump on the Sydney Harbour Bridge, loosening the trailer.

He said the company would learn from its mistakes.

“The trucks are all over the pits with the RMS at the moment and we’re working with them to assure everything is to the regulations,” Mr Vinci told 2GB Radio .

The 61-year-old driver at the centre of the spill was charged with not complying with loading requirements and will appear at Downing Centre Local Court on February 26.