Updated

Tests confirmed the deadly strain of bird flu in Egypt, as France reported a probable first case Friday and the United Nations expressed growing concern about the virus' spread through West Africa.

Egypt reported Friday that 18-20 dead birds had tested positive for bird flu. A U.N. official said tests confirmed an outbreak of the deadly H5N1 strain that has swept out of Southeast Asia into Europe, the Middle East and Africa.

Egypt's health ministry was preparing to declare a state of emergency, the government said.

The French agriculture ministry said Friday that it found the nation's "probable" first case of H5N1 bird flu virus in a dead wild duck. The ministry said tests confirmed that the duck found in the southeast Ain region had H5 bird flu and that it was believed to be the deadly N1 strain. Further tests were being conducted, the ministry said.

Bird flu has killed 91 people in Turkey and in Asia since 2003, with most victims infected directly by sick birds, according to the World Health Organization. Scientists fear the H5N1 virus could mutate to a form more easily passed between humans and spark a human flu pandemic.

In Egypt, Dr. Talib Elham of the U.N. Food and Agriculture Organization said the disease apparently had moved north to Cairo in an infected turkey taken to market in the capital.

Other outbreaks were found in flocks in backyard gardens and rooftop coops in Giza, across the Nile river from Cairo. Positive tests also were reported from birds in the southern Egyptian cities of Minya and Qena.

Egypt is the largest Arab country and the population — which often lives in cramped conditions — depends heavily on chickens and turkeys for food. Millions of Egyptians keep chickens in gardens and rooftop coops.

Egypt has no confirmed cases in humans.

Germany confirmed 10 more cases of avian flu in birds Friday and warned state governments to brace for the disease to spread through the country. The 10 birds found on a northern island had the H5N1 strain, the federal animal health institute said Friday. They followed three previously confirmed cases.

German Agriculture Minister Horst Seehofer said he expected the disease to continue to spread throughout the country and urged state governments to prepare for a worst-case scenario.

"We must expect that this will expand to other geographical areas," Seehofer.

The U.N. Food and Agriculture Organization expressed growing concern that bird flu could spread beyond Nigeria to other West African countries, and it proposed giving farmers incentives to report possible outbreaks early.

"The highly pathogenic avian influenza virus poses a very serious threat to animal health in West Africa," said the agency's chief veterinary officer, Joseph Domenech.

"If a poultry epidemic should develop beyond the boundaries of Nigeria the effects would be disastrous for the livelihoods and the food security of millions of people."

Bird flu has affected at least three of Nigeria's 36 states. Five other states and the country's northern neighbor, Niger, are investigating suspected bird deaths from H5N1.

West Africa already is threatened by severe malnutrition, with more than 2 million people vulnerable to acute hunger in Niger alone.

Domenech said incentives should be offered to poor African farmers to report suspected cases immediately.

"If the government is just there to kill the animals and cull them there is the possibility that the farmers won't report cases," FAO official Juan Lubroth said.

The agency has long expressed concern about possible outbreaks in Africa, where poor countries are ill-equipped to contain the virus.

In Nigeria, authorities knew of the existence of a deadly bird flu strain up to 19 days before informing the public of Africa's first documented case.

Officials in Denmark and the Netherlands were testing dead wild birds Friday and warned it was only a matter of time before the disease reached their countries.

Vietnam is allowing commercial farms to resume hatching and restocking chickens since there have no bird flu outbreaks among poultry over the past two months, Hoang Kim Giao, deputy director of the agriculture ministry breeding department, said Friday.

"The restriction has been lifted because bird flu has been brought under control," he said.