Some Uber drivers are operating illegally in New Zealand, the NZTA says.

​Uber drivers facing fines of up to $10,000 for breaking the law will be supported by the company.

Uber last week decided its New Zealand drivers no longer needed a passenger (P) endorsement, which was issued after checks on drivers' medical, criminal, behavioural and driving histories.

On Friday, Transport Minister Simon Bridges said this was illegal.

"P Endorsements are the law today and will continue to be," Bridges said.

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Asked if Uber would pay any fines incurred by its drivers, a spokesman for the company said: "We will stand by our drivers 100 per cent. We will stand by our driver partners and we will support them".

Uber wanted to see the Government change regulations, so "ride-sharers" would no longer need passenger endorsements.

Drivers would instead undergo a criminal background check from the Ministry of Justice and an NZTA driving history check, the spokesman said.

NZTA's process was unaffordable for some drivers, Uber's spokesman said.

However, NZTA manager Celia Patrick said Uber's checks were "far less rigorous" than the official passenger endorsements.

"It shouldn't be purely around the dollars, it needs to be around ensuring the safety of passengers," Patrick said.

She urged passengers to "request the information, ask to see the P endorsement and make an informed decision about who you're travelling with".

The NZTA has already issued six warnings against Uber drivers. One driver was issued with a "notice to cease driving" after he was found "medically unfit to carry passengers", Patrick said.

Patrick was concerned some Uber drivers could be "inadvertently getting on the wrong side of the law". She said the NZTA would contact and warn drivers caught acting illegally, before proceeding with legal action.

While drivers are liable to large fines, NZTA could not say if any legal action could be taken against Uber.

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