Ljubljana - Slovenia's five trade union associations have asked the Constitutional Court to have its say on a provision in the latest Covid relief law that raises the pay ceiling in the single public sector wage system only for the benefit of doctors and dentists.

Presenting their petition to reporters on Thursday, the ZSSS, Pergam, Neodvisnost, KS 90 and the KSJS confederation of public sector unions said they were asking the court to stay the implementation of the provision pending its final decision.

They disagree with the government that the maximum wage rise for just one group of public employees has anything to do with emergency measures aimed at tackling the Covid-19 emergency.

"It's a cuckoo's egg that enabled the government to avoid the prescribed procedures to change the wage brackets set down by law, and legally prescribed talks to agree the changes with trade unions representing the public sector," said KSJS head Branimir Štrukelj.

Their main argument in the constitutional challenge is violation of the right to referendum.

After the National Assembly passed the latest Covid relief package in late December it also banned a referendum on it. However, the unions argue the constitution does not make it possible to ban a referendum on changes to pay brackets.

Their counsel Iztok Ščernjavič said they were challenging the law over mistakes in the legislative procedure. As the provision on the pay ceiling was included in the emergency bill, the citizens' right to a referendum was denied.

Ščernjavič also criticised the upper chamber of parliament for giving up its right to impose a suspensive veto on emergency laws.

Štrukelj said the constitutional challenge was in defence of the "erosion of the rule of law". To show there is a lawful way, they called on the government to start lawful systemic procedures to amend wage brackets, but have not received an answer yet.

The unions also accused the government of double standards, pointing to a lack of progress over the 26,000 public sector employees who get an extra allowance just to earn the minimum wage, saying all employees in the public sector should be treated the same way.

The government has said the rise in the doctors' top wage bracket is but provisional until the end of 2022. Health Minister Janez Poklukar said it did not mean a pay rise yet but gave the ministry a basis to set out negotiating points.

Meanwhile, FIDES, the trade union of doctors and dentists, said earlier this week it was prepared to use all industrial means at its disposal for the higher pay ceiling to be put into effect and for healthcare to get its own wage system.