NHK has learned that mass culling of chickens amid a record bird flu outbreak in Japan has been hampered by a shortage of suitable land in 16 of the country's 47 prefectures.

Over 17 million chickens have been culled this season because of the bird flu, the highest number ever. About 9 percent of hens kept for their eggs in Japan have been disposed of.

Local governments and poultry farms usually bury the culled birds to prevent the spread of the virus.

NHK contacted 26 prefectures that reported outbreaks this season and learned that 16 were having problems.

Twelve prefectures, including Kagoshima and Hiroshima, reported 14 cases in which land that had been readied beforehand was found to be unusable.

Seven prefectures, such as Kagawa and Hokkaido, reported nine cases of land shortages.

There was also at least one case where water filled a hole that was dug.

Sakoda Yoshihiro, a professor at Hokkaido University, points out that Japan does not have much spare land to begin with.

He suggests it is time to drastically review measures to deal with bird flu outbreaks, such as promoting incineration or reducing the number of birds to be culled.