India needs more funding to deal with the "massive threat" of bird flu, the prime minister told a conference of international bird flu experts in the Indian capital.

Prime Minister Manmohan Singh said the international community must renew its commitments to deal with the disease, which has killed more than 200 people since 2003 and could potentially lead to a deadly human pandemic. "Many pledges have been fulfilled," said Singh, according to a transcript of his speech. "However we need more funding support."

John Lange, the United States' special representative for avian and pandemic influenza, said the US would announce later in the conference a large increase in US funding.

The United States had already pledged $434 million in international assistance a year ago, Lange said.

India, home to millions of farmers who keep poultry in their yards, has seen three major outbreaks of bird flu in poultry since 2006, all of which were brought under control, but has not reported any human cases.

Singh stressed that countries must focus on animal health as well as human health to deal with the disease, and that measures to prevent outbreaks in backyard poultry remained limited for now. "The best available strategy is to control it at the level of the animal," he said. "Investments in public health will be unproductive without ensuring the health of our livestock." He said an Indian laboratory had developed a poultry vaccine using the Indian strain, and other research efforts continued.

For now, humans usually contract the virus only after close contact with infected birds, with the virus killing nearly two-thirds of the people it infects. But experts worry it may mutate into a form easily transmitted from person to person, leading to a pandemic.

Around a fifth of humanity could fall ill should there be another flu pandemic, according to estimates cited by the World Health Organisation, with catastrophic effects on the global economy.

There have been roughly three flu pandemics each century since the 16th century, the WHO says.