In announcing the new tactic, the Police Trade Union of Slovenia (PSS) said it had filed referendum initiatives - the first step in seeking a popular vote - for four laws.

Arguing that it has been forced into stepping up the strike by the government's unwillingness to negotiate, the PSS said that the campaign was aimed at checking the decision of the government.

Referendum initiatives were filed on the changes to the environmental protection act, changes to the financial derivatives act, changes to the Slovenske železnice act and changes to the court fees act.

To file a referendum initiative, a group must collect 2,500 signatures. This forces parliament to allow the collection of 40,000 verified voter signatures needed to call the referendum. The law being challenged is suspended for the 35-day period in which voter signatures are collected.

The trade union said it was giving the voters a chance to decide whether they wanted to challenge any of the laws by contributing signatures, but would actively campaign against the laws.

"Acting as citizens and voters, we have decided to scrutinise decisions of the government, including laws which it has entered into parliamentary procedure. We intend to pursue this course of action until suitable solutions are found for police."

The government continues "to treat security as self given and ignore that...it is a result of the hard work and dedication of police officers". "We cannot trust a government which refuses to make good on past promises," the trade union said in a statement.

There is no mention whether the second police trade union, SPS, is included in the new campaign.

In the strike started on 19 November police are seeking better pay and working conditions in line with promises given before 2010, when the economic crisis forced cuts in public sector pay.

This is the second time in less than a month that a group has decided to arm-twist the government with threats of referendum challenges against government laws not directly related to their demands.

In March, a newly-established trade union representing workers who commute to Austria demanded talks on the income tax rules in the country by filing a referendum initiative on changes to asylum legislation.

The representatives of the Migrant Workers Trade Union were subsequently received by Prime Minister Miro Cerar for talks, although their tactic prompted criticism from some legal experts.