The incident occurred in Navalpur Ratoy village in Haldharpur area in this district where the woman noticed that a group of men were harassing her teenaged daughter.
She intervened but the miscreants poured acid on her and fled, the police.
The woman was then rushed to a district hospital from where she was referred to Varanasi in view of the grievous nature of her injuries.
Circle Officer, City, Pankaj Kumar Singh said an FIR has been registered and probe is on.
While the opposition has been attacking the state government over the issue, Chief Minister Yogi Adityanath has repeatedly asserted that criminals will be made to face strict action.
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