OSLO (Reuters) - Norwegian police searched on Friday for three baby penguins stolen from an aquarium in a suspected student prank, with time running out for the tiny chicks that cannot survive long outside a nest.

"It's a tragedy," Tor Erik Standal, head of the Aalesund Aquarium on Norway's west coast, told Reuters after the three Humboldt penguin chicks and one egg vanished early on Thursday.

Police charged five or six youths on Friday for endangering animals by breaking into the aquarium, based on video surveillance evidence, police investigator Rita Thoresen told Reuters.

"None of them admits taking the penguins," she said.

More than 100 volunteers turned out to help the police search for the flightless birds in the countryside around the aquarium, Standal said. The chicks are about three weeks old and weigh only around 300 grams (10 ounces) each.

"They will not be able to survive for much longer," he said. "They should have been in their nest for maybe 2-3 more weeks before they go outside."

May is a time of celebration for high school graduates in Norway, often including drunkenness and pranks or dares such as going without sleep for 72 hours, kissing a policeman or even, on one occasion, hugging the central bank governor.

(Reporting by Alister Doyle; Editing by Robin Pomeroy)