The UPTET scheduled to be held on Sunday was cancelled after a question paper for the exam was leaked, an officer here announced shortly before the exam was to begin.

The Uttar Pradesh Special Task Force (STF) arrested 23 people last night using technical and other intelligence from different cities of the state, Additional Director General Law and Order Prashant Kumar said here.

UP Chief Minister Yogi Adityanath said the culprits will be booked under the National Security Act and Gangster Act.

He also ordered reconvening of the exam within a month.

"A question paper was leaked. I issued an order to cancel the examination and arrest the entire racket. Instructions were also given to conduct the exam within a month, and that no candidate should be charged additional fee, he said addressing a function in Deoria district on Sunday.

He said orders were given to transport the students back to their home towns in UPSRTC buses free of cost on the basis of their admit cards.

"Those who have committed this act should listen that cases will be registered against them under the Gangster Act and the National Security Act, he said.

Later in a tweet in Hindi, the CM said properties will be seized by the government of those involved in the leak.

Close to 20 lakh candidates were to appear for the Uttar Pradesh Teachers Eligibility Test (UPTET) on Sunday.

Earlier in the day, the ADG said that those arrested included four from Lucknow, 13 from Prayagraj, three by the Meerut STF and one from Kaushambi district.

"A photocopy of the question paper was obtained from them, which was shared with the government. It came to light that the copy bore the same set of questions as did the official question paper, he said.

"Immediately it was decided by the government that the exam needs to be cancelled and reconvened in the coming one month.

All expenses for the exam will be borne by the government. The candidates will not have to pay the fees or fill the examination form," he added.

The officer said the matter will be probed by the UP STF, and people or organisations involved in the leak will not be spared.

The question paper of the examination had not reached the examination centres till Sunday morning.

Items seized from accused included mobile phones and photocopy of question papers.

"Apart from UP, some people of Bihar have also been caught in this matter. Either the solver gang leaks the question paper, or a solver (person impersonating the candidate) appears instead of the candidate," Kumar said, adding more arrests will be made.

The situation at centres was under control and announcements were made there to urge the candidates to go back to their homes, added the officer.

Adityanath in a tweet said, "The state government is standing with the candidates of UPTET, and a re-exam will be held in a transparent manner within one month."

"Those who have played with the future of our young brothers and sisters will not be spared. People who have caused inconvenience to you will be definitely punished. Your government is committed to conduct the exams in a fair and transparent manner, he said in another tweet.

UP's Basic Education minister Satish Dwivedi said the exam - in both shifts -- was cancelled immediately after the leak came to surface and promised a strict action against the culprits.

Samajwadi Party chief Akhilesh Yadav blamed the BJP government for the leak saying such incidents have become a norm under its rule.

"Cancellation of the UPTET examination due to the leak of the question paper is like playing with the future of nearly 20 lakh aspirants. Paper leaks, cancellation of the examination is common in the BJP government, he said in a Hindi tweet.

Corruption in education in UP is at an all-time high. The unemployed will usher in a revolution, and there will be a change in 2022.

Congress general secretary Priyanka Gandhi Vadra too alleged that corruption in education and recruitment has become common under the BJP.

"Corruption in recruitment, leaking of question papers has become the identity of the BJP government, she said in tweet posted in Hindi.

Today the efforts of lakhs of youths have gone in vain following leak of the question paper. Every time there is a question paper leak, the government of Yogi Adityanath saves the top dogs. This is the reason corruption is at its peak," she added.