Speaking in Parkes on Friday Mr Donato said a concession for heavy vehicles in primary production, introduced in 1998, had not been applied by Roads and Maritime Services (RMS).

However a spokesperson for the Minister for Roads, Maritime and Freight Melinda Pavey said the problem was unintentional and the result of “poorly worded legislation”.

According to Mr Donato “the documents speak for themselves”.

“They clearly show 95 per cent of people affected live outside the Sydney-metropolitan area,” he said

“Over 184,000 vehicles are affected and this is really a kick in the guts for farmers who are doing it extremely tough in one of the worst droughts we’ve seen in recent living memory.

“They have been fleeced of this money and the government should pay it back.

“The government has been aware of it since February of this year, they’ve sat on their hands and done nothing about it.

“It wasn’t disclosed to the public, the farmers weren’t told they’d been overcharged and now they should get what’s rightfully theirs.”

A spokesperson for the  Minister for Roads, Maritime and Freight Melinda Pavey said the problem had been “the result of poorly worded legislation in 1995”.

“The changes were only meant to impact light vehicles, but they had an unintended consequence on heavy vehicles,” the spokesperson said.

“We are now doing our homework into what we can do to fix it.

“Currently heavy vehicle drivers are receiving a 55 per cent discount on their registration, an average saving of $1259.”

Parkes farmer Wayne Dunford said he was surprised to hear about the report.

“We have two prime movers and four trailers that would have fallen under that banner for the last 20 odd years,” he said.

“There would be a lot of other farmers who would have similar numbers, so as individuals it would add up to a reasonable amount of money.

“Every dollar counts more so than ever at the moment given the drought and the expense of people running their business through it.

“It would be pretty good for the government to sort it out very quickly and put that money back into the rural community where they can actually use it to keep them going.

“It will be interesting to see what they do with it and how they sort it out.”

Mr Dunford said he thought people would be upset once the news become public knowledge.

“I think the anger will be around the fact that they have sat on their hands for six months,” he said.

“They haven’t even alerted people that something’s gone wrong and that they are going to try and make good with it.”

Mr Donato called on all farmers to demand a refund now.

“I encourage all affected farmers to contact their local Roads and Maritime Services office to inquire about getting their refund,” he said.

“When there’s a budget surplus of over $3 billion, farmers don’t deserve more delays.”