DHAKA, July 15 (Reuters) - Bird flu has spread to another district in Bangladesh forcing health and veterinary workers to cull 2,000 chickens, officials said on Sunday.

The latest case was reported from a village in Naogaon district, 250 km (156 miles) northwest of the capital, Dhaka, said a senior officer of the fisheries and livestock ministry.

Bird flu was first detected near the capital in March and has since spread mostly to northern districts.

Seventeen out of Bangladesh"e;s 64 districts have been affected by the virus, but there have been no reported cases of human infection.

The virus has forced authorities to cull 257,000 chickens and destroy more than 2.2 million eggs since its outbreak.

About four million Bangladeshis are directly or indirectly associated with poultry farming.