“About 450 workers were taken to different hospitals,” Alam said, adding that most have since been released.
Alam said the owners shut down the plant while police sent samples of the water to a laboratory for testing.
The factory called Rose Limited was also hit by mass food poisoning on Friday night when about 200 workers were taken to hospital after eating dinner supplied by the workplace, Mustafizur Rahman, a director of the Industrial Police, told AFP.
The incident is the latest setback for the industry. It follows the collapse of a building housing garment factories in April that killed more than 1,100 people and triggered renewed scrutiny of “made-in-Bangladesh” clothes commonly sold in the West.
In recent weeks more than 1,000 workers have fallen ill at several garment factories — a phenomenon that medical experts have said could be a type of mass hysteria triggered by psychological distress.
Some 600 workers fell sick at a factory outside the capital in early June, but microbiologists found nothing wrong with drinking water supplied.
Experts instead blamed the incident on a psychogenic illness or mass hysteria, which struck the country about eight years ago and forced dozens of schools and factories to close.
The condition appears highly contagious — as soon as one or two workers fall sick, others are immediately struck with similar symptoms, with extremely hot weather contributing to their vulnerability.
Experts said the illness can be triggered by big events or tragedies like the Rana Plaza disaster in which five factories collapsed within minutes on April 24, trapping over 3,000 workers and killing 1,129.