Underwatertimes.com News Service - September 26, 2007 14:47 EST

The main section of Malaysia's largest aquarium has been shut after about 600 fish died mysteriously, possibly because of deliberate poisoning, officials said Wednesday.

The fish, including sharks, stingrays and groupers, died within hours Monday evening at the Langkawi Underwater World, said an official at the center who declined to be named because he is not authorized to make public statements.

Langkawi police chief Mohamed Ali Jamaludin said the water in the tanks smelled of gasoline and was believed to be contaminated with a pesticide or poison. Police are awaiting the results of a water analysis, he said.

"This is not a work of negligence," he told The Associated Press, saying that police believed it was deliberate sabotage of the tourist attraction in Langkawi, a resort island in northern Malaysia.

The center, which features some 5,000 ocean and freshwater fish, has offered a 10,000 ringgit (US$2,900; EUR2,100) reward to anyone who provides information leading to an arrest, he said.

The center's marine section and its main attraction - a 15-meter (50-foot) walkthrough tank containing 6 million liters (1.6 million gallons) of sea water - have been shut since the incident, the aquarium official said.

The official couldn't say when it would be reopened.

A rain forest section with plants and animals remained open but there have been few visitors since Tuesday, he said. The center received an average of 1,000 visitors a day before the incident, he added