An Albanian high-school class pulled off a dangerous April fool's prank on their teacher when all pupils took sedatives and fell asleep in class, reports said.

All 20 students of a class in a school in Saranda, on Albania's southern Adriatic coast, swallowed one or two Diazepam pills. They obtained the drug, similar to Valium, in a pharmacy, reports said.

When the teacher saw his entire class slip in deep slumber, he grew frantic with fear and had all his students transported to a hospital, where the joke unravelled.

The school director described the prank as "collective idiocy".