"We've ordered officials to increase patrols for dams countrywide and at the same time we have demanded increased laboratory examination of water samples taken from these dams," Water Resources Agency chief Chen Shen-hsien told reporters.

The rare order -- the second since the September 11, 2001 terrorist attacks on the United States -- came one day after police, alerted by a farmer, found some 27 kilograms (59 pounds six ounces) of rat poison in Chinsha reservoir on Kinmen, an island off the southeastern Chinese city of Xiamen.

Chinsha reservoir head Wung Tze-pao said there was no danger to Kinmen residents as the polluted water was being held within a dike and had not flowed into the main reservoir.

"There is no need to panic," he said.

Samples of water from the reservoir were flown back to Taiwan for examination.

Health officials said the rat poison contained brodifacum, a highly toxic anticoagulant that can cause fatal hemorrhages or strokes.

Workers found three other packs of the rat bait in the dike Tuesday morning while authorities were trying to pump the water that may be polluted into the ocean.

Police were investigating who dumped the poison but authorities said it did not appear to be a deliberate attempt to poison the water supply.

"The possibility of an evil-minded move to poison the reservoir is low because it does not supply household water due to drought" since late April, said Chen.

The poison was routinely distributed to farmers to kill rodents.

The reservoir can hold up to 80,000 tonnes or enough to provide Kinmen with water for a month.

TERRA.WIRE