Hong Kong officials said Tuesday they were extending for four months a ban on live poultry imports from mainland China to guard against the potentially deadly H7N9 avian flu.

The city imposed a 21-day ban in January and culled some 20,000 chickens after the virus was found in one batch of imported chickens.

Health minister Ko Wing-man told reporters there are plans to set up a facility where imported poultry can be quarantined to ensure they are disease-free before being sent to market.

After four months "we will liaise with mainland authorities about the supply of live poultry to Hong Kong", he said.

Before the import ban, local birds were mixed with those from mainland China in the city's only wholesale market, in the Cheung Sha Wan district.

The H7N9 outbreak began in China in February 2013. In January there were 127 confirmed human cases there, of whom 31 died, making it by far the worst month of the outbreak.

Since December Hong Kong has reported five human H7N9 infections, of whom three have died.