DHAKA, Feb 17 (Reuters) - Bird flu has spread to another district in Bangladesh despite massive culling by authorities to control the outbreak, officials said on Sunday, bringing the number of affected districts to 43 out of 64.

The new case of the avian influenza was found in Shariatpur, in the southwest, livestock officials said.

The outbreak occured as health workers culled more than 160,000 chickens at a poultry farm in the capital Dhaka following detection of the bird flu virus.

"This will be the biggest number of poultry birds to be culled at a single farm since the outbreak of the deadly virus," said Salehuddin Khan, a director of the livestock department.

More than 600,000 birds have been culled across the country against the virus since March 2007, but it continues to spread and now covers nearly two-thirds of the country of more than 140 million people partly due to a lack of awareness.

No human infections have been reported in Bangladesh, a densely populated nation with millions of backyard poultry and thousands of chicken farms.

The government has enhanced compensation for poultry farmers to encourage farmers to report and kill sick birds as part of efforts to stamp out the outbreak.

Authorities also used loudspeakers and distributed leaflets in villages, urging people to report sick fowls and bury dead birds.

Experts fear the H5N1 strain could mutate or combine with the highly contagious seasonal influenza virus and spark a pandemic, especially in countries such as Bangladesh where people live in close proximity to backyard poultry. (Reporting by Ruma Paul; Editing by Sanjeev Miglani)

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