Queensland unions are demanding the state government reimburse them for challenging campaign spending laws in the High Court.

Queensland unions are pursuing the state government for legal costs after it relaxed potentially unconstitutional campaign spending laws.

The Liberal National Party government had introduced laws requiring unions to ballot members before spending $10,000 on a political campaign.

But almost a year after they came into effect, the government this week announced it would dump the provision, following a High Court challenge.

Queensland unions had spent $100,000 challenging the laws.

Queensland Council of Unions assistant general secretary Ros McLennan said on Friday their lawyers had written to Attorney-General Jarrod Bleijie demanding reimbursement for running a High Court case.

“This legislation was a blatant legal exercise to shut down legitimate union campaigns against unpopular government decisions,” she said.

The Together public service union, which joined the campaign, said the law was unconstitutional and the government should compensate unions.

“There’s no legal structure, at this stage, to guarantee that money will be reimbursed,” secretary Alex Scott told reporters.

“They have a moral duty to return that money.”

But Mr Bleijie declined to say if the funds would be reimbursed.

“The matter’s before the High Court so it would be completely inappropriate for me to comment,” he told reporters.

Since the laws were introduced, the High Court upheld a union challenge to similar laws in NSW.

The QCU initiated the High Court challenge to Queensland’s laws with support from the state police, nurses and teachers’ unions.