Romania and Bulgaria have reported outbreaks of highly pathogenic avian influenza among poultry, Reuters reported, citing the World Organisation for Animal Health (WOAH) on Friday, as Europe faces a seasonal upturn in the deadly disease.

The spread of avian influenza, commonly called bird flu, has raised concerns among governments and the poultry industry after it ravaged flocks around the world in recent years, disrupting supply, fuelling higher food prices and raising the risk of human transmission.

In Romania, the H5N1 virus was detected in a flock of 120 backyard poultry in the village of Tiganesti near the border with Bulgaria, causing the death of 28 birds, the Paris-based WOAH said, citing a report from the Romanian authorities.

Bulgaria, meanwhile, reported earlier this week outbreaks of an H5-type avian influenza virus on two poultry farms, WOAH said in a separate notice.

One outbreak in Malko Konare in the Pazardzhik region killed 380 birds out of a flock of 171,911, while another outbreak in Debelets in the region of Veliko Tarnovo killed 5,420 out of 395,045 farm poultry, WOAH said, quoting details from the Bulgarian authorities.

The intergovernmental body last week reported that Poland, the European Union's largest poultry producer, had detected H5N1 bird flu virus among poultry in the north of the country.