More than 250 public schools across NSW are closed as teachers strike for 24 hours over pay and conditions.

Thousands of teachers marched up Sydney’s Macquarie Street on Wednesday, rallying outside parliament house and calling for “more than thanks” amid a shortage of teachers.

They want a pay rise above the 2.5 per cent cap on public sector wage rises that has stood in NSW since 2011 as well as extra time for lesson planning and other paperwork.

The NSW Education Department lists 259 schools as “not operating” on Wednesday and parents are being urged to keep children home with minimal supervision at schools that are open.

Education Minister Sarah Mitchell said the disruption to students and parents caused by the strike was “frustrating and disappointing”.

NSW Teachers Federation president Angelo Gavrielatos said children were having their learning disrupted every day due to a lack of teachers causing classes to merge.

“To say their learning is being disrupted is a massive understatement, and yet the premier and the minister wants to lecture us about disruption?” he said.

“If the state won’t pay teachers more they won’t be able to fill the staff shortage that government reports have warned of for years.”

Greenacre Public School principal Melissa Proctor said she could never find enough teachers.

Specialist teachers were teaching in areas they weren’t qualified in while executive staff took classes as well too, amid a shortage that was getting worse.

“Amazing teachers are leaving our profession because they can’t cope with the ever increasing demand of the workload and the impact that has on their own families and wellbeing,” Ms Proctor said.

Ms Mitchell asked the union to cancel the industrial action on Tuesday after Premier Dominic Perrottet indicated he would lift the 2.5 per cent wage increase cap for public sector workers in the June 21 budget.

“We are actively looking at this as part of the budget and not just for teachers, but all our frontline staff and we made that clear,” Ms Mitchell told the Nine Network on Wednesday.

Uralla Central School principal Michael Rathborne said the budget promise was akin to a pat on the head and accused Ms Mitchell of denying there was a problem with staffing in the state’s schools.

“It’s not good enough,” he said.

“Things have never been worse.”

Staff absences led to at least one class being cancelled every day at his school and he and his deputy principal regularly had to teach classes themselves.

His search for a school counsellor, after seven were churned through the school in eight years, was on its third round of recruiting and there was only one day a week when his school’s more than 300 students could see one, he said.

Labor education spokeswoman Prue Car accused the government of being out of touch, denying pay rises to its public sector workforce while wages for politicians’ support staff went up.

Chiefs of staff for government ministers were effectively given a 10 per cent pay rise recently, with the creation of a new salary band that increases the top salary from $320,000 to $354,201.

Ms Mitchell told Sydney radio 2GB that figure was an upper limit and no ministerial staff earned the top salary.

Public sector workforce wage rises amount to billions of dollars and the government has competing priorities that need to be balanced, Ms Mitchell said.

“These are major decisions that should actually be made as part of a proper budget process, not in response to union demands,” she said.