A whistleblower claims one major transporter has routinely ignored proper maintenance, putting lives at risk from unsafe trucks around the country.

A supposed employee of Cootes Transport has told public broadcaster ABC’s Four Corners program that many of the company’s vehicles should not be allowed on Australian roads.

Similar claims came from an interviewee who said he worked for Queensland company Blenners Transport.

Cootes has been the subject of a complete safety audit since an accident at Mona Vale near Sydney last year, when a fuel tanker rolled and caught fire, leaving two people dead.

The whistleblower, allegedly a long-time employee of Cootes Transport, said that maintenance shifts had been cut back while the company was under the ownership of a private equity firm, CHAMP.

The recent safety blitz on Cootes’ trucks revealed more than 200 defects, many of them major malfunctions in brakes, steering and suspension.

“Trucks have caught on fire. Trucks were simply well and truly over their service times,” the whistleblower said in the interview aired last night.

“I know for a fact of trucks being driven with very poor repair jobs done on them. They should never have been on the road - they should've been put on a tow truck, but they continue to work.”

“In the meantime, they just don't get looked at until they break down somewhere or something falls off. Mudguards fall off, sets of wheels fall off, brake hubs disappear never to be seen again,” he said.

Similar claims from another interviewee on the same program, who appeared anonymously claiming he knew a key factor in the Mona Vale crash.

“Cootes won the contract to cart fuel to 7/11 service stations to begin on the April 1, 2013,” said the supposed Cootes staff member.

“We didn't know how they were going to do that contract on April 1 because they were short of vehicles, prime movers and trailers, so in desperation they were using any equipment they could get their hands on.

“I know ... that trailer [in the Mona Vale accident] was brought out of retirement several months earlier.”

“That was gone over to some degree, [then] put back into service with an old prime mover to do the 7/11 jobs.”

Head of the compliance operations for NSW Roads and Maritime Services, Paul Endicott, said the failings at Cootes were “probably the worst I have seen.”

Systemic breaches of fatigue management laws and regulations were highlighted in another transport company too, in an interview with former operations manager at the business, Stephen Gleeson.

“The fatigue was just on an unprecedented level that I'd never seen,” Mr Gleeson said of the conditions at Blenners.

“My belief at that time was that the supermarkets, [as well as] McCain's, Nestle ... were applying pressure to Blenners. Blenners was applying the pressure on the drivers and this was all a big, ridiculous situation.”

The situation recently led to 45 active and former drivers from Blenners Transport pleading guilty to over 150 offences, complete with fines totalling more than $65,000.