Drivers of wheelchair vehicles, mini buses and cars estimated yesterday up to 300 Hunter children - and 3000 in NSW - would be without transport to school on Monday.

The NSW Education Department said on Thursday about 300 students in the NSW Assisted School Travel Scheme would be affected by late disruptions to the scheme.

It said some drivers had withdrawn at the last minute because they deemed runs were financially unviable.

Hunter drivers hit back yesterday and said the state government had bungled the tender process.

It began when they imposed new pay rates and extra red tape on drivers in July despite having awarded tenders.

Under the changes drivers will no longer receive a daily rate on top of their rate for each kilometre travelled.

Daily rates help cover costs that include expensive specialist vehicles, travel to school runs, driver pay awards, petrol, insurance, public liability and vehicle registration fees.

Then, the government did not assign school runs until early this week and drivers had days to do the sums, with many pulling out.

For example a Maitland mini bus operator who takes a wheelchair-bound Medowie child two kilometres to school would get $38 for the trip, down from $140.

Driver Greg Heard said it appeared the government had awarded only 10 per cent of the school runs in Maitland and many children in the area would be left waiting.

Mr Heard has been driving children to school for 37 years and had more than 80 students on his books among his 22 vehicle fleet last year. Now he has seven students.

"Parents haven't been told anything," he said.

One operator said that up to 80 students in Newcastle would be without a lift.

Charlestown hire cars general manager Bryen Smith said after doing school runs for 20 years they had to reject about one-third, many with wheelchair-bound students.

"We cannot run a vehicle for what they're prepared to pay," Mr Smith said.

Neville Short who has been a Maitland driver for 13 years and runs four vehicles, said he had been offered two students a day in 2012, when his company normally transported 12.

A NSW Education Department spokesman said they had a large number of contractors who were happy to accept the new pay rates and some were getting more than in the past.

He said there was no indication that it was any more than 300 students affected.

Parent Kate Kirsop said she was not happy with the government and would have to take her daughter to school.