Smooth, complex, soft, salty and strong — yet delicate, luscious and elegant.

Those are just a few of the adjectives used to describe Westvleteren beer, which is often hailed by aficionados as one of the best in the world.

Part of the mystique rested in its exclusivity. For more than 170 years, the beer has been produced and distributed solely by the Trappist monks of St. Sixtus Abbey in Westvleteren, a village in western Belgium.

But that changed last week when a branch of Jan Linders, a Dutch supermarket chain, sold more than 7,000 bottles without the monks’ permission, and at 10 euros each, several times higher than the original price.

The supermarket said it had obtained the beer through “a number of links,” according to Gineke Wilms, its marketing manager, in comments cited by a Dutch daily.