Half of all courses at The University of Queensland could be affected as full-time staff stage a 24-hour strike over pay and conditions.

Up to 1000 staff at Queensland’s biggest university are expected to walk off the job as part of strike action for better pay and conditions.

The National Tertiary Education Union says academic and professional staff at The University of Queensland (UQ) will strike for 24 hours from Tuesday morning.

The union has accused the university of languishing behind others when it comes to pay, workloads and indigenous employment.

The union’s UQ representative, associate professor Andrew Bonnell, says staff are also protesting against the “casualisation” of the workforce, given half of all classes are now being taught by casuals.

It was causing an unacceptable level of anxiety and uncertainty for staff, he said.

Prof Bonnell said full-time teaching staff had plunged since 2012, despite students numbers rising by about 20 per cent, or by 8000 students, over five years.

The history lecturer said he expected “close to 1000” staff would be staying home during the strike action.

Up to half of all students attending the university on Tuesday could be affected, Prof Bonnell said.

“There are some schools where most of the full-time teaching staff are (union) members,” he told AAP.

“So it could be up to half the courses that could be affected in some way.”

Prof Bonnell said the strike action was a last resort after 18 months of negotiations that have not yet seen staff even given a pay offer.

But a UQ spokeswoman said the union may be overstating concerns, given negotiations were close to being finalised on most issues and only about half of UQ’s union membership voted for strike action.

“It is regrettable that the union has decided to take action which may impact on some students early in the semester,” the spokeswoman said.

So that staff are not disadvantaged by the negotiating process, UQ said it has paid a 2.5 per cent salary increase from 1 January 2014, outside of any scheduled pay rise.

Union members will be forming a symbolic picket line at the university’s main entrance on Tuesday morning.