AMSTERDAM - Amsterdam's mayor said Wednesday that he would formally ban students from smoking marijuana at school, making the Dutch capital the first city in the Netherlands to do so.

Eberhard van der Laan's introduction of an ordinance that in other countries either already exists or seems so obvious it would not require a rule is the result of the Netherlands' unique drug policy. Under the "tolerance" principle, marijuana is technically illegal here, but police cannot prosecute people for possession of small amounts.

That is the loophole that made possible Amsterdam's "coffee shops" - cafes where marijuana is sold openly. It has also had the side effect that Dutch children are frequently exposed to the drug in public areas.

City spokeswoman Iris Reshef says schools have always forbidden marijuana but found it difficult to enforce the policy when students smoked on or near campus and challenged administrators to do anything about it.

After a change in national law, the city will be able to declare as of Jan. 1 "no toking zones" - areas such as schools and playgrounds where weed-smoking is forbidden - under a public-nuisance ordinance. Police can then levy fines against students or anyone else who flouts the rules.

The move is closely paired with a decision by the new government to ditch plans for a national "weed pass" that would have blocked tourists from buying marijuana.

That was a measure years in the making, and desired by southern cities such as Maastricht that have been flooded with dealers from Belgium and Germany who drive across the border to buy marijuana in bulk. But the weed pass was opposed by Amsterdam, where drug tourists are not generally seen as causing many problems.

Last month, van der Laan proclaimed that coffee shops would stay open for tourists after all.