The first man to be found guilty of sexually harassing women in a public place has been fined €280, of which €180 is conditional on him not reoffending again.

The man was spotted by undercover council wardens grabbing a woman by her hips against her will in central Rotterdam on August 8. They intervened and issued him with a summons.

Sexual harassment in public places has been a criminal offence in the Netherlands since July 1 after previous attempts to use local bylaws to bring in similar rules flopped.

The new law states that it is a crime to harass people sexually by hissing, intimidating them, making sexual remarks or following them in public places.

Figures from national statistics agency CBS indicate two in three women between the ages of 12 and 25 are harassed in public places and a third feel unsafe because of it.

There is “increased social awareness of the harmfulness and undesirability of sexual harassment” and this has translated into stronger disapproval and more enforcement and prosecution, the magistrate said, in sentencing.

Warden and police unions earlier expressed doubts about the viability of the law. Police union ACP called the added task “a big challenge” for wardens and said it would not be easy for them to catch street sex pests in the act.

The public prosecution department said on Wednesday that 14 other cases have so far come to light. Three were dismissed because of a lack of evidence, two are awaiting a court ruling and nine others still have to come to court.

The man in the first case has a previous conviction for indecent assault, urination in public and breach of the peace.