Veterinary workers in India have begun culling tens of thousands of chickens in an attempt to combat a fresh outbreak of bird flu in West Bengal.
The disease surfaced in the region in January. More than one million birds were slaughtered.
But about a month ago officials said the situation was under control.
Both outbreaks involve the potentially fatal H5N1 virus, although so far there have been no reports of humans being infected in India.
Scientists fear that the virus could eventually mutate into a form easily transmitted between humans, leading to a pandemic that could kill millions worldwide.
Officials say that the latest outbreak has been discovered in West Bengal's Murshidabad district, where 900 chickens and ducks died over the last fortnight.
In January, the H5N1 virus affected hit 13 of the state's 19 districts, including Murshidabad, bringing down poultry sales by more than 70%.
The authorities had to cull more than 3.4 million birds in the state after the World Health Organization (WHO) described January's outbreak as the worst in in India.
"The virus could have been transmitted through smuggling of poultry from bordering Bangladesh, which is hit by avian flu," said West Bengal's animal resources minister, Anisur Rahaman.
But he also conceded that the disease may have resurfaced because some villagers hid their potentially infected birds from the teams sent in to destroy them in January.
Some villagers insisted that their chickens were healthy, while others refused to give theirs up because they said that government compensation levels were inadequate.
The problems were compounded by poor and illiterate farmers sometimes being misinformed about basic hygiene.
Officials in Bangladesh say that virus spread to another district last week, affecting 47 out of 64 districts in the country.