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.