The Indian state of West Bengal, battling the country's worst outbreak of deadly bird flu, appealed on Saturday to the federal government to send "all possible help to defeat" the virus.
The call by state animal resources minister Anisur Rahaman came as authorities struggled to stop the disease spreading beyond the 12 out of 19 state districts already affected.
"We have to control the disease immediately as the deadly H5N1 virus has been spreading fast," Rahaman said, adding "avian flu is knocking on the doors of Kolkata," the eastern state's congested capital of 13.5 million people.
"I'm urging the federal government to send all possible help to defeat the virus before it affects the humans," he told AFP.
New Delhi has already sent medical teams and other assistance to the state.
But three days of heavy rains have held up efforts to slaughter poultry, turning some rural dirt roads into muddy rivers and making it impossible for health teams to reach chicken farms in the poverty-ridden state.
Rahaman said he was concerned by reports some villagers in rural areas were eating slaughtered chickens.
"We don't understand why people do not understand the dangers of the disease despite repeated warnings," he said, adding children were still playing with chickens.
Humans typically catch the disease by coming into direct contact with infected poultry, but experts fear the H5N1 strain may mutate into a form easily transmissible between people.
India has not had any human cases of bird flu. But Rahaman said he feared the disease would spread to humans with hundreds of people reporting flu symptoms.
Panic about bird flu has gripped Kolkata after news spread that the disease had reached the city outskirts on Friday. Workers at entry points to Kolkata were disinfecting vehicles entering the city.
Few shops were selling poultry in Kolkata on Saturday.
"Not a single customer has come to my shop since the morning," said Malati Mondal, a store owner.
The government has raised the number of chickens to be slaughtered to 2.5 million, up from 2.2 million, Rahaman said, adding 1.3 million had been killed so far.
The outbreak was first reported in the village of Margram, 240 kilometres (150 miles) from Kolkata. It is India's third -- and by far worst -- outbreak of the disease.
Meanwhile, in neighbouring Bangladesh from where the Indian outbreak is believed to have spread, bird flu has struck districts recovering from the worst cyclone in decades that hit in November.
The outbreak has "happened at a time when farmers were trying to rebuild their lives after the cyclone. Many farmers have been devastated," said Barguna district's local administrator Shafayat Hossain.
Barguna bore the main brunt when cyclone Sidr slammed into Bangladesh's coast, leaving at least 3,300 people dead.
"It's a huge set back for cyclone victims. A lot depend on poultry as their livelihood," said Adi Spijkers of the UN Food and Agriculture Organisation.
No human infections have been reported in Bangladesh, but Spijkers' remarks came amid a rise in outbreaks in the country's southern, central and northern districts.
Since Bangladesh's first bird flu outbreak in February 2007, the disease has been detected in 26 of the country's 64 districts.
Officials said the situation worsened in January but remains under control in the impoverished country of 144 million people. Experts differ, saying it is worse than the government claims, with farmers not reporting many cases.