TAIPEI, April 19 (Reuters) - A rare tornado touched down in southern Taiwan, wrecking houses and uprooting utility poles, a Central Weather Bureau official said.

The twister hit Tainan County at 1:30 a.m. on Wednesday as unstable weather associated with a cold front passed through the area, said Daniel Wu, director of the bureau's forecasting centre.

No one was injured from the tornado, which lasted about an hour later, he added.

Taiwan media said about 20 houses were damaged, utilities were cut and pigs died after the were plucked from the ground and thrown through the air. One newspaper showed a picture of a pig slumped over the top of a fence.

"I suddenly couldn't see anything. It was like the end of the world," said one witness.

The twister was about 50 metres wide and moved at a relatively brisk 50 kph, Wu said.

Taiwan's spring weather is unstable as cold fronts bring heavy winds, hard rain and dramatic temperature changes.

The island gets about two tornadoes a year.

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