A mass search for piranha fish in the Liujiang River has been called off, and the offer of a reward for catching one withdrawn by the local government.

The government of Liuzhou in the Guangxi Zhuang autonomous region, had called on its residents to hunt for the piranhas - which are normally native to South America - on Tuesday after two people were reportedly attacked by three of them.

The authorities had offered 1,000 yuan ($157) for every dangerous snapper caught.

Professional fishermen and residents took part in the search but no piranhas were caught in four days and now officials have cancelled the rewards, and asked for nets not to be used because they say too many fish were being killed in the frenzy.

Wei Yongwen, head of the local livestock and fishery bureau, said lots of local fish breeds were found dead in the nets, and he feared damaging the ecological balance in the river.

"No more fishing nets should be used in the hunt - but residents are still encouraged to try and catch piranhas with a hook and line," he said.

Three piranhas were reported to have been seen in the river, one of which bit the left hand of a man when he was bathing his dog, as well as biting the finger of his friend on Saturday.

The local government said they may have been released by other residents, who often buy them as unusual pets.