The signs are written in both Thai and English with the message "Beware of the Monkeys". They were placed at popular tourist attractions such as Long Beach, Monkey Bay and on Phi Phi Island.
Duangporn Paothong, director of Phi Phi Island Hospital, said about 600 people were treated in hospital after being attacked by monkeys last year, and 75 per cent of the victims were foreigners.
She warned tourists not to feed the monkeys living along the beaches because they will develop a bad habit of becoming hostile towards people who do not give them food.
People who get bitten by the monkeys should immediately contact physicians so that they can receive tetanus shots, Dr Duangporn said.
Since the beginning of this year, about 50 tourists have reportedly been attacked by monkeys, a significant decline from last year.
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