A legal loophole was used to keep NCS buses able to do train replacement services.

​NZTA continues to have safety concerns about a Wellington bus company despite the High Court saying it is okay to operate.

The stoush between the Transport Agency meant Boss Transport - which runs NCS buses, including some of those replacing Wellington trains over the holiday break - jumped through a legal loophole for 18 hours so it could continue to operate after NZTA issued a cease-to-operate order.

Its owner, Malcolm Little, believed his company was being unfairly targeted by NZTA and the Police Commercial Vehicle Safety Team (CVST).

Infractions were as minor as some diesel splatter or a wrongly-coloured safety feature, he said.

Meredith Connell managing partner and NZTA regulatory compliance lead Steve Haszard said the agency had adopted "a tougher and more active approach to regulatory compliance and enforcement".

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"We are addressing issues of non-compliance where public safety could be at risk, giving priority to the most urgent cases. Where suspension or revocation is necessary to ensure public safety, the Transport Agency is taking action."

ROBERT KITCHIN/STUFF Boss Transport, which runs NCS buses, is in a war of words and court action with NZTA.

​NZTA stood by the safety concerns it had leading to it revoking the transport service licence from Boss Transport on December 20, he said.

Boss had applied for an injunction to allow it to continue to operate and had appealed NZTA's revocation.

On Christmas Eve, the High Court gave it an interim order allowing it to operate till February, when the case would go back to court for the full appeal to be heard.

But, between the cease-to-operate order and the High Court interim order, Boss Transport worked a legal loophole to continue to operate.

For 18 hours it leased its fleet to Auckland operator Kiwi Coaches meaning it could continue to operate under the Auckland operator's transport service licence.

ROBERT KITCHIN/STUFF NCS buses - run by Boss Transport - waiting at Wellington Railway Station as train replacements over Christmas break.

Little, from Boss Transport, and Kiwi Coaches director Calvin West have each confirmed this happened. Both said Boss Transport was being unfairly targeted.

Little believed NZTA was concerned about the sudden expansion of its fleet.

One infraction was a little bit of diesel spray on the exterior of a tank, and another involved an inspector taking exception to the colour of a protective rubbery cover over a metal seat frame, he said.

A brand-new bus was ordered off the road because the inspector didn't approve of the tinted covering over an emergency exit. NZTA later confirmed it approved of the covering, Little said.

"It is totally ridiculous. NZTA are in total disarray. They are going above and beyond to make a point," he said.

Boss Transport began privately-run commuter services in places like Wainuiomata, Hutt Valley, and Porirua after seeing shortfalls in Wellington's July bus overhaul. It bought 33 NZ Bus buses to meet demand.

It also often runs train-replacement buses, which it is currently doing on Wellington lines, and runs charter services.

Ian Ladd, from train operator Transdev, said it contracted a number of bus operators for train replacements.

"Part of the requirements is that the operators and vehicles comply with the relevant transport regulations and safety standards," he said.

"We are unaware of any issues and would respond appropriately to any concerns if any were raised."

Inspector Kelly Ryan, from police CVST, said cases were taken on a case-by-case basis and police did not operate with any ill-intent.

"If we notice during inspections that there seems to be recurring issues with the same company or operator, we will meet with them to discuss the issues and assist them with solutions to prevent any further issues," Ryan said.

"It's about working together to keep everybody safe on our roads because road safety is everyone's responsibility.

"Our staff in CVST absolutely committed to doing their best every day to keep people safe on New Zealand roads and will continue to do so."

NZTA would not comment further while the appeal was pending.