The virus may be spreading despite control measures such as slaughtering poultry flocks in infected areas and the outbreak had to be confronted with a transparent well-resourced program, the UN Food and Agriculture Organization (FAO) said.
"The highly pathogenic avian influenza virus H5N1 could become endemic in Turkey and poses a serious risk to neighbouring countries," senior animal health officer Juan Lubroth said in a statement.
"The virus may be spreading despite the control measures already taken. Far more human and animal exposure to the virus will occur if strict containment does not isolate all known and unknown locations where the bird flu virus is currently present," he said.
Turkey insisted Wednesday it had the outbreak under control after confirming 13 people were being treated for the H5N1 virus that last week claimed the lives of two children in the country's southeast.
They are the first victims of the disease outside Southeast Asia and China where more than 70 have died in the past two years.
Mark Danzon, regional director for Europe for the World Health Organisation (WHO), described Ankara's handling of the crisis as "appropriate" and said management of the health crisis was at the correct level.
Humans can get bird flu from contact with infected animals, but scientists fear millions of people could die if the virus mutates with human strains of flu and becomes highly contagious.
The FAO, which has sent a team of experts to Turkey, called on neighbouring Armenia, Azerbaijan, Georgia, Iraq, Iran and Syria to be on high alert and to ensure their populations are fully informed about the bird flu risk.
"Turkey needs to apply a centrally coordinated and country-wide control campaign based on efficient local actions carried out in a transparent manner," Lubroth said.
"Infected poultry should be reported immediately and all internationally recommended control measures should be used in outbreak areas, including humane culling, strict isolation and, if and when appropriate, vaccination."
Veterinary services should receive political support and funding to investigate suspected outbreaks while poultry owners had to be briefed on disease symptoms and control and prevention, the FAO said.
"Immediate reporting by poultry keepers and their community leaders is the biggest safeguard for peoples health status," Lubroth said.
The FAO called for a halt on all transfers of birds in affected areas, particularly during the holiday season when movements increased, and said villages could help slow the spread of the disease by limiting contact between local poultry flocks.