Deputy Premier John Barilaro has poured fuel on an explosive spat with a union after his party was accused of hindering bushfire preparations across NSW with “crippling” staff cuts.

A political blame game has broken – even as bushfires continue to rage – with Mr Barilaro criticising the National Parks and Wildlife Service for not doing enough hazard reduction in the lead-up to the fire season.

The Public Service Association, which represents park rangers, hit back by saying Mr Barilaro was “tastelessly blaming” public servants after his government slashed staff numbers.

The PSA says there’s been a 35 per cent cut to fire-trained positions in the state’s national parks which are now being managed by “skeleton staff”.

But the NSW government says the number of firefighters in national parks has increased from 1050 in 2011 to 1226 in 2019.

Mr Barilaro refused to back down when he was grilled in state parliament on Wednesday.

“The truth of the matter is that we still live with (former premier) Bob Carr’s legacy – lock up the forest and let it burn,” he said.

“I make no apology for my comments. The PSA went out and fibbed in relation to the reduction of rangers dealing with fires in national parks.”

Mr Barilaro in a separate statement said he wouldn’t be lectured by those pushing a “green-left ideology”.

“There are things to learn out of every bushfire emergency and what’s clear is that more hazard reduction work needs to be done during times where it is safe to do so,” he told AAP.

“We can’t be dictated to by a green-left ideology that advocates locking up bushland and leaving it.”

PSA acting general secretary Troy Wright said politicians should focus on preparedness – not political ideology.

“If the origins of these catastrophic fires across the state are in national parks then it is the National Party and part of the Berejiklian government that are responsible for the lack of preparedness,” he said in a statement.

“It is the complete absence of proper funding, not some mercurial green movement as the Nationals allege.”

Australian Workers’ Union national secretary Daniel Walton is calling for an inquiry into firefighter staffing levels in national parks.

“Every day we are hearing from members across the state about how their resourcing is poorer than it’s ever been and the knock-on effects that’s having,” he said in a statement on Wednesday.

“The AWU has been warning for years that fire services are grossly under-resourced.

“We just don’t have adequate resources to deal with catastrophic events that are becoming increasingly common due to climate change.”