The exam was scheduled to be held at 10 a.m. on Sunday.
According to reports, the paper went viral on several WhatsApp groups in Mathura, Ghaziabad, and Bulandshahr just before the exam began.
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Uttar Pradesh Additional Director General of Police (ADG), Law and Order, Prashant Kumar said, "UPTET 2021 examination scheduled to be held today stands cancelled due to alleged paper leak."
He said that dozens of suspects have been detained by STF in the paper leak case and the investigation is on.
The Uttar Pradesh Basic Education Board (UPBEB) will conduct the UPTET exam again after one month. The UPBEB has further notified that candidates will not have to pay any fees again for the exam. The exact date of the UPTET exam will be notified in due course of time.
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Meanwhile, the state government has also asked students to travel back to their home free on state roadways buses by just showing their admit cards.
The Special Task Force (STF) of the Uttar Pradesh Police has already launched an investigation into the matter. .