At least 40 invitees, including 12 women, to a wedding in Bhatpara, on the city’s northern fringe, were taken ill after eating biryani late on Wednesday. They were admitted to Bhatpara State General Hospital, from where 35 were released later. The condition of the remaining five was stated to be critical on Thursday.

Preliminary police investigation blamed it on the biryani gone stale. “The mutton biryani served to the guests on Wednesday night had been cooked the previous day,” said an official of Jagaddal police station.

S. Dutta, superintendent of the Bhatpara hospital, said the patients, who started pouring into the emergency unit from 10 pm on Wednesday, were showing symptoms of “food poisoning”.