Hong Kong has praised the success of its primate birth control program

HONG KONG has hailed the success of a birth control program for the city's wild monkeys, saying the primates' numbers have dropped 15 per cent over four years.

Officials said the latest monkey census showed the population stood at 1965 last year, down from 2320 in 2008 - a year after the city started fertility controls for the primates using methods including vasectomies.

The conservation department said about 70 per cent of the monkeys had been treated under the "monkey desexing program". All treated monkeys were implanted with a microchip for identification.

The government decided to take action after receiving numerous complaints from the public including reports of aggressive monkeys chasing hikers for food.

It is illegal to feed monkeys in the southern Chinese city, punishable with a fine of up to HK$10,000 ($1200).