THOUSANDS of people could be slapped with fines for offences that would never have attracted police attention in the past under sweeping reforms to police powers.

Experts fear swearing in public, with a fine of $100, will be a major money spinner and could become the weapon of choice for frustrated officers on the beat.

Queensland Premier Anna Bligh announced the new powers for the state's police to issue on-the-spot notices for public nuisance offences.

Ms Bligh said the move would increase efficiency, save time and fast-track more important matters in the courts by stopping minor public nuisance offenders from clogging the justice system.

She said the measures, targeting offences such as public urination, disorderly conduct and abusive language, would save the Government between $18 million and $30 million.

The power to issue on-the-spot fines of between $100 and $300 could result in public nuisance prosecutions soaring 20 per cent, based on figures from a 12-month trial in South Brisbane and Townsville.

In 2008-2009 terms, that could see 5500 more people slapped with the offence across Queensland each year.

Ms Bligh said it was hard to estimate if the 20 per cent increase would hold true right across the state.

She attributed it to police having more time "on the beat" because the on-the-spot powers saved hours compared to the time spent processing an arrest.

But an evaluation of the trial by Griffith University said evidence existed that, given on-the-spot powers, police were more likely to issue tickets in situations unlikely to be considered criminal before the courts.

The NSW Ombudsman said the problem particularly concerned police fining people for swearing, saying: "The words spoken would not be considered offensive if the matter was to be determined by a court."

Queensland Council of Civil Liberties president Michael Cope said the powers were a concern when it came to offensive language and would see public nuisance offence rates soar.

"This will become the thing police just slap on someone whenever they aren't happy," Mr Cope said. "No one will fight them and ultimately people who are homeless or young will bear the brunt of this."

Trial figures showed 1 per cent of those charged had appealed.

Police Minister Neil Roberts said inappropriate behaviour in public places was not acceptable and would not be tolerated.

The legislation will be introduced to Parliament later this year, with the new powers to take effect by 2011.