A tow truck operator says the reason towies won't move the vehicles illegally blocking streets outside Parliament is not due to safety concerns - it's because they sympathise with the protesters.

There's growing frustration over an apparent lack of action to remove the vehicles, and an offer of free parking at Sky Stadium has largely been ignored.

In recent days, police have referred to concerns held by tow truck companies who have been threatened by protesters.

Yesterday, Police Commissioner Andrew Coster tried to allay their fears, and appealed for towies to come and help.

"Clearly we will have police staff working alongside tow trucks to ensure the safety of all concerned," he says.

"It is a major operation for us to remove the large number of vehicles around those streets and we have from the outset of this had very great reluctance from tow operators to support us in clearing this situation.

"So part of what we would like to do today is to appeal to those who are tow operators to come forward and help us sort this out."

But Greg Cox, who owns Wellington's Cox Heavy Salvage, says safety concerns are not what's stopping tow companies getting involved.

"There's all different reasons being put forward, but the reason that the majority of my colleagues don't want to put their tow trucks out there is because they are sympathetic to what's going on in Parliament," he says.

Not wanting to sour their relationship with police, Cox says some operators have made up excuses for not lending a hand in the towing operation.

"One of the Wellington operators said how he can't do it now - 'We have to isolate'."

He says police have not been misleading in their public statements about "safety concerns" - that was just what the towies had been telling them.

"They're saying what they're hearing," he says.

Cox has been been contacted twice by police asking for help with the towing operation.

He has been in touch with 10 or so other operators, and believes the majority of the industry has similar views.

"From the people who've rung me, text me, the feeling's pretty much mutual right through the country. There's not a business that hasn't been impacted by mandate, and everybody understands that."

Also, if he turned up at Parliament with a fleet of tow trucks it would be a very bad look for his business: "That'd be the worst advertising I'd get," he says.

"Contractors and transport operators have been feeling us out to say, 'Guys, what are your feelings, you know, we don't really want to see your tow trucks in here. We want you to stay on side'."

The question should not be what police and the council are going to do to move the vehicles, he says, but rather what the politicians are going to do about it.

"They should come out and talk to the people that they represent. You can't deny these people a hearing and if that had happened straight away I very much doubt they'd still be there," he says.

"You don't turn the sprinklers on and put loud music over the top - that's arrogant. That really is not the way to actually entice people to come to the table and talk."

He believes there's a simple way forward - "dialogue".

"It's deep-seated [and] I actually think they underestimated how deep-seated it was.

"I think the fact that all the salvage industry has supported them, they are now starting to realise it is very deep-seated."

The Defence Force is also in discussion with police after receiving a request to help with the towing operation.

In a statement it says: "There are a number of factors to be considered not least the suitability of military recovery vehicles for this task and the availability of trained personnel, which we have discussed with NZ Police. Discussions are ongoing."

-RNZ/Matthew Theunissen.