A damning report into the New Zealand Transport Agency (NZTA) has found it failed to do its job and keep people on our roads safe. 

It comes as Newshub can reveal that former staff of the agency raised concerns years ago, but say they were ignored by senior managers. 

One man Newshub spoke to used to work as a senior technical adviser for the NZTA. He helped the agency regulate heavy vehicles like trucks.

The man - who can't be identified - says he told bosses years ago that the agency was failing to crackdown on dodgy operators, but his warnings were ignored.

"The agency didn't see itself as a regulator - it saw itself as a customer service organisation," he says.

He told Newshub that agency bosses treated transport operators as customers and wanted to ensure they were productive. 

And as such, they didn't want to interfere. 

When asked how big the customer focus was at the agency, he said it was "huge - all consuming".

Those same concerns have been echoed in a report released today.

The report  warns that a "powerful focus on customer service" "adversely influenced...decision-making".

It also stated that "regulatory responsibilities have been overshadowed by preoccupations with other NZTA functions".

"The Transport Agency was encouraged to focus on roads at the expense of its regulatory mandate," says Transport Minister Phil Twyford.

The problems with the agency have been evident for years. 

In 2016, Newshub discovered NZTA contractors were helping students sitting P endorsements cheat on their tests. 

Then we found serious flaws with the way some NZTA-approved contractors carried out testing for truck, bus, taxi and forklift drivers. 

Since October last year, more than 70,000 vehicle owners have been told they've been issued with suspect warrants.  

And the Transport Minister even thinks the agency and the ministry's failings have contributed to our massive road toll - but Twyford is blaming the previous Government. 

"The period we are talking about is the last nine years of National Government."

National's transport spokesperson Chris Bishop disagrees.

"Phil Twyford is using what's a very serious issue to make a political attack on the National Party," says Bishop. "Frankly, he should be better than that."

As for the former NZTA worker, he believes the agency's former boss Geoff Dangerfield should bear some responsibility. 

He says he raised his concerns with him multiple times.

"The regulatory process was not followed at all, in my view, but the guys on the ground worked damn hard to do it."

When asked if it was the managers who were blocking the process, he answered: "In my view, yes".

Dangerfield - who didn't respond to requests for comment - and others, including Fergus Gammie, have since resigned. 

"[They have] not been held to account, and I've found that frustrating," the former worker says.

It's now a case of trying to regain the public's confidence in the agency.

To do this, Twyford says he'll establish a new director of land transport to oversee the agency's regulatory functions. 

New staff are being employed, and Twyford's putting $45 million into what the agency should have been doing - regulating road safety.