CALCUTTA, India - Authorities have confirmed new cases of bird flu in eastern India today, a month after they slaughtered nearly four million birds in the same state to stem the country's worst ever outbreak.

State workers are preparing to kill birds that may have been infected in villages in West Bengal.

Officials say roughly 900 birds have died of the deadly H5N1 strain of the virus over the past week in two villages where bird flu was previously confirmed.

Bird flu broke out in West Bengal in January, prompting the mass slaughter. State officials lifted a ban on the sale of poultry in most affected areas in early February.

Officials did not say whether they would reinstate the ban given the fresh outbreak.

No humans in India are known to have caught the disease, which has killed at least 235 people worldwide, according to the World Health Organization. Experts fear it may mutate into a new form that spreads easily among people, potentially sparking a pandemic.