Czech authorities are preparing to destroy up to 220,000 hens on a poultry farm in the west of the country after avian influenza was discovered there last week, in the biggest outbreak to date, reported Reuters.

Avian influenza was reported last Friday at the farm located 150 km (90 miles) west from Prague, which can house up to 750,000 chickens, after an increase of deaths in one of three halls there.

The Czech Republic's State Veterinary Administration (SVS) said on Tuesday that since checks revealed the infection only in one of the halls, the majority of the flock could be spared.

"The whole (population of the) hall will have to be culled," said Petr Majer, SVS spokesman.