WARSAW (AFP) - Poland was hit by a fourth case of deadly H5N1 bird flu Monday when the disease was discovered at a poultry farm, the agriculture minister confirmed.

"The new case was discovered in the village of Saldowo, near to Biezun, (central Poland) close to other recent cases," farms minister Marek Sawicki told reporters in Warsaw.

"Just as in the previous cases all the chickens will be culled," agriculture ministry spokeswoman Malgorzata Ksiazyk.

Three previous cases of H5N1-type bird flu, which is fatal to humans, were discovered earlier this month at chicken and turkey farms 120 kilometers (72 miles) northwest of Warsaw.

Veterinary authorities ordered a cull of 110,000 chickens in the area on Sunday.

A 30-kilometer isolation zone was established Monday around the farm where the newest case was discovered. Smaller zones were created around the three other contaminated farms in nearby villages.

The cases of H5N1 are the first to be recorded in Poland among domestic fowl. Last year the disease was discovered only among wild birds.