ROME - Countries are making progress in fighting bird flu but concerns remain for some nations -- especially Indonesia, Egypt and Nigeria -- where human contamination is still possible, the United Nations said Wednesday.

Scientists and officials gathering in Rome for a three-day technical meeting on bird flu said that in most cases the virus is rapidly detected and kept under control, as most countries are equipped with improved response systems. However, in nations that combine a high density of population and unsafe poultry management, the situation remains serious.

"There is great improvement of preparedness and response," with countries in Asia, Eastern Europe and the Middle East rapidly detecting and eliminating the virus, said Joseph Domenech, the chief veterinary officer of the U.N. Food and Agriculture Organization. "What makes the battle against avian influenza so difficult are the many high-risk poultry production and marketing practices that still continue in many countries."

Domenech said that Indonesia presents the highest danger due to the great number of people having direct contact with poultry. Indonesia has more than 13,000 live poultry markets where birds of different origins are mixed, according to the Rome-based agency.

The experts stressed the need for continued surveillance and closer international cooperation, as well as improved hygienic conditions, specially in markets.

The H5N1 strain of bird flu has devastated poultry stocks since 2003 and killed at least 191 people worldwide. Experts fear that the virus could mutate into a form easily spread between people, potentially igniting a flu pandemic.

"The persistence of H5N1 despite all efforts to tackle it is a concern," said David Nabarro, the U.N. official coordinating the global fight against bird flu. "We need to have a combination of political will and solidarity ... to make sure all nations are pandemic-ready."