U.N. officials are urging Indonesia to take more aggressive steps to contain the bird flu epidemic in poultry before the current human outbreak escalates and spreads beyond the country's borders.

With avian influenza now diagnosed among birds in two-thirds of the country's provinces, Indonesia must begin the immediate culling of poultry in infected areas and revamp its campaign to vaccinate fowl against the virus, according to officials from the U.N. Food and Agriculture Organization.

The Indonesian government has so far balked at following guidelines set by the agency that call for the slaughter of all poultry in the area surrounding an outbreak. Indonesian agriculture officials said they had instead resorted to immunization. But the effort to vaccinate poultry across the country has stalled in many provinces, with coverage far below the threshold required for it be effective, animal health experts said.

The U.N. agency's chief veterinarian, Joseph Domenech, issued a statement last month airing concerns about Indonesia's performance and calling on the government to make avian flu a national priority. He announced that U.N. officials had offered to help the government improve its virus-control policies.

Carolyn Benigno, the agency's animal health officer for Asia, said in an interview this past week that the agency has continued to speak with the Indonesians about the steps they should take. "They have new provinces getting outbreaks and occurrences of human deaths. It really raised an alarm," she said.

Since July, international testing has confirmed five human cases of bird flu in Indonesia, including three deaths. Health officials say the actual toll is higher and will probably rise.

International health experts cite Indonesia as one of the weakest links in efforts to head off a potential global pandemic, in part because of the country's large size and the poor condition of its public health system. Though it remains difficult for humans to catch the disease, the World Health Organization has warned that the virus could mutate into a form easily contracted by and passed among people, potentially killing tens of millions worldwide.

Indonesian officials say they have been constrained by a lack of funding and scientific knowledge about the disease. But Agriculture Minister Anton Apriyantono said in an interview that Indonesia has succeeded in limiting the outbreak.

"It's not easy fighting," he said. "Things are getting better now, much better. Things are getting in order."

Since early last year, the government has followed a nine-point program to contain bird flu in poultry, taking such steps as improving safeguards on farms and monitoring flocks, as well as vaccinating birds and, to a limited extent, culling them, Apriyantono said.

According to the U.N. agriculture agency, all poultry should be slaughtered within two to six miles of any outbreak, depending on the specific conditions of the infection. "When there is an outbreak, culling is the only way," Domenech said in an interview from the agency's headquarters in Rome.

The U.S. secretary of health and human services, Mike Leavitt, addressed the value of culling chickens and ducks during his visit to Jakarta this past week for discussions with Indonesian officials about bird flu. He told reporters that culling was "an important strategy, because when the combination of people and birds come together, that's when the virus begins to change, evolve, skip."

Apriyantono, however, countered that Indonesia could not carry out this policy because there was not enough money to compensate farmers.

Yet the Agriculture Ministry last year spent only two-fifths of its available avian flu budget, returning more than $10 million to the national treasury, said Tri Satya Putri Naipospos, former national director of animal health

Instead of culling, the government promised U.N. health experts it would vaccinate poultry nationwide and supplied about 300 million doses to local animal health offices. Chasing down free-range chickens and ducks to inject them was never going to be easy. But national and local agriculture officials admitted that in many cases, government veterinarians at the district or county level never tried.

By the end of last year, no district in Indonesia had reported using more than 50 percent of the doses provided, and some used as little as 11 percent, Naipospos said. The actual figures were likely even lower. Local officials at times inflated the results because they were paid a small bonus by the government for each vaccination recorded, animal health experts said.

U.N. officials said that at least 90 percent of the poultry in an immediate area must be vaccinated for the effort to be effective.

Indonesian and international health experts said they believed the infection had been contained in large commercial farms, where it first appeared, but has now spread to poultry in smaller farms and to the chickens raised in millions of back yards.

But monitoring progress in commercial farms has been difficult because farm operators have consistently barred entry to inspectors, prevented government testing of flocks and failed to report outbreaks, according to Naipospos and other animal health experts. Local health officers have not challenged the farmers, who often have close ties to senior officials, and the national government failed to adopt new laws that could have compelled the conglomerates to cooperate, Naipospos said.

Don P. Utoyo, coordinator of the Indonesian Poultry Forum, which represents poultry companies, said they had tried to work with animal health officers. If commercial outfits barred entry to local inspectors, it was because farmers were afraid that local officials would inadvertently contaminate the farms or seek to collect taxes, he said.

A rooster and hen look for food at a bird market in Indonesia, where the effort to vaccinate poultry has largely stalled.