Kharagpur/Calcutta, April 19: Tomorrow’s state Joint Entrance Examination has been put off indefinitely, affecting over 76,000 examinees, after plain-clothes police busted a question paper racket in Kharagpur this morning.

Board officials said the rescheduled JEM (known as JEE till last year) was unlikely to be held before the panchayat polls ended on May 18.

The JEM board has matched the leaked photocopies of the physics, chemistry and biology question papers with the originals and found them identical.

“It is hereby decided to postpone the examination, scheduled on April 20 in West Bengal and Tripura. The revised dates will be announced later,’’ board chairman Siddhartha Dutta announced.

This is the first time a state joint entrance examination — the gateway to engineering and medical colleges — has been cancelled because of a question leak. A CID team led by P. Neerajnayan reached Kharagpur tonight.

Although the board had kept a second and third set of question papers ready as back-up, officials said they didn’t have the infrastructure to send them to each exam centre in less than a day.

“It’s almost impossible to fix a new date before the panchayat polls. The examination must be held on a single day and it has to be a Sunday. Some national-level exams are lined up from next week, which means the coming Sundays won’t be available,’’ a board official said.

Last year, after a police probe revealed that several dummy candidates had sat the exam, the CID had arrested 43 impersonators.

“Forty of them are on bail. Sixteen were from Calcutta and the rest from Bihar, Jharkhand and Orissa. The trial is continuing and the investigations may lead to more arrests,’’ board lawyer Subrata Mukhopadhyay said.

The Kharagpur police were tipped off last night that JEM question papers were selling at Rs 2.5 lakh, and given the cellphone number of the alleged seller, Arun Choudhury.

“Officers called up Choudhury last night itself, identifying themselves as customers,’’ West Midnapore police chief R. Rajsekharan said.

Asked how they got his number, the police told Choudhury “a friend” had given it to them.

“We said the friend had got it from a candidate who cleared last year’s engineering exam with the help of question papers leaked by Choudhury,’’ an officer said.

On Choudhury’s instructions, an inspector-in-charge and a woman sub-inspector – who wore a yellow sari and posed as her male colleague’s wife -- reached Ghatal, 100km from Kharagpur, around 8.30am today.

“Come to Ghatal and I’ll tell you where to go from there,’’ Choudhury had said, and had in turn been told to look out for a woman in a yellow sari.

When the “couple” called Choudhury from Ghatal, they were told to go to the nearby Panskura bus stand. Within half an hour, a man arrived and introduced himself as Mihir Dandapat, Choudhury’s agent.

He asked the “customers’’ to follow him to a nearby sweetmeat shop. “He asked if we had brought the money. We showed him the Rs 1 lakh we were carrying,” the officer said.

Called by Dandapat, Choudhury hurried in around 10am, carrying photocopies of the physics, chemistry and biology papers. The male officer ran a quick glance over them and handed over the cash.

By then, according to shop owner Bibhas Ghosh, the woman officer had edged away unnoticed. She took out her mobile and made a call. Within minutes, three vehicles full of police pulled up at the shop.

Choudhury and Dandapat will be produced in court tomorrow.

The West Midnapore police got in touch with the higher education department and were asked to bring the papers to Calcutta to be matched against the originals.

A search of Choudhury’s home yielded a second set of photocopies of the mathematics, physics and chemistry papers. Officers suspect the gang had already passed on several photocopies and are probing if it had leaked questions before past exams, too.

The police are likely to visit the Saraswati Press, where the papers were printed, and the JEM board.

“These are the only two places from where the papers could have been leaked,” an officer said. “Choudhury must have had access to people there.”

The joint entrance board was set up in 1962 when it conducted exams only for engineering colleges. Medical entrance tests were incorporated in 1972.

Till last year, the board was a part of Bengal Engineering and Science University. This year, it was converted into an autonomous body.