OSLO—An acute butter shortage in Norway, one of the world’s richest countries, has left people worrying how to bake their Christmas goodies with store shelves emptied and prices through the roof.

The shortfall, expected to last into January, amounts to between 500 and 1,000 tons, said Tine, Norway’s main dairy company, while online sellers have offered 500-gram packs for up to 350 euros ($465).

The dire shortage poses a serious challenge for Norwegians who are trying to finish their traditional Christmas baking — a task which usually requires them to make at least seven different kinds of biscuits.

The shortfall has been blamed on a rainy summer that cut into feed production and therefore dairy output, but also the ballooning popularity of a low-carbohydrate, fat-rich diet that has sent demand for butter soaring.

“Compared to 2010, demand has grown by as much as 30 percent,” Tine spokesman Lars Galtung told AFP.

Last Friday, customs officers stopped a Russian at the Norwegian-Swedish border and seized 90 kilos (198 pounds) of butter stashed in his car.