KUALA LUMPUR Three dams and 10 water treatment plants in a Malaysian state have been closed to the public after an anonymous caller threatened to poison one of the dams, officials said today.

A spokesman for the Penang Water Supply Corp. said the Air Itam, Teluk Bahang and Mengkuang dams on northern Penang island have been closed since Friday as a precautionary measure.

But water in the state remained safe for consumption and there was no disruption to supplies, he told AFP .

Penang chief minister Koh Tsu Koon was quoted by the New Straits Times as saying that the company received a call from a man on Friday afternoon warning that the island's oldest and smallest Air Itam dam would be poisoned.

Crank call

The caller's phone number has been recorded and police were investigating the case, he said.

Officials said no signs of contamination have been detected and believed it was a crank call but were taking no chances and have stepped up security at all the dams and the 10 water treatment plants.

All three dams were previously opened to the public for recreation and it was unclear how long they would be shut.

Security in the whole state, which is a popular tourist destination, have been tightened since the October 12 bomb blast on the Indonesian resort island of Bali which killed more than 190 people, Koh added. AFP