People with computer know-how and access to usernames and passwords of schools are suspected to be the key operatives in siphoning off funds meant for higher secondary students of government and state-aided schools to buy tabs or smartphones for digital learning.

A one-time grant of ₹10,000 to Class XI and XII students is given under the state government's Taruner Swapna scheme.

Over the past few days, many cases have been reported from various districts where this money has been transferred to unknown bank accounts within the state and outside, including Delhi, Jharkhand and Bihar. Senior police officers suspect computer-literate persons are involved in the case.

"We are collecting details of bank accounts where the money has been transferred instead of students' bank accounts. We are zeroing in on the locations and taking steps to freeze such accounts,” said Pradeep Kumar Yadav, the Malda SP.

Police suspicion of the role of "computer-literates" in the crime stems from arrests already made. In Malda, police arrested Rocky Sheikh of Baishnabnagar, a contractual computer teacher appointed by a private company at a state-aided school at Kaliachak-III block. Others own or work at cyber cafes.

The Malda arrests were made after five schools filed police complaints alleging that their students did not receive the grant.

“Three senior officers led by the additional superintendent of police (headquarters) are investigating the scam. We are also planning to form a SIT (special investigation team) for the probe,” Yadav added.

During preliminary investigation, police officers found that the fraudsters either hacked the state's website with the student database or used usernames and passwords to log in.

“They changed bank details of hundreds of students and replaced them with bank account numbers from where they could withdraw money,” said a police officer.

“Some schools with poor infrastructure and employees entrust cybercafes with login IDs and passwords to upload student data. We suspect the alteration was also done from these cafes,” Yadav added.

When the scam came to light, questions were also raised about the role of headmasters and teachers-in-charge of the schools as they can access the state government's portal with student account details.

Chandan Maiti, general secretary of the Advance Society for Headmasters & Headmistresses, pointed out that in July, some headmasters in East Midnapore had alerted authorities about some altered bank account numbers. "We don't believe a scam of this scale can happen without the state education department officials who can access the back-end of the portal,” Maiti aded, demanding a CID probe.

Some web developers with whom The Telegraph spoke said there was less chance of hacking.

"The scammers probably gained backend access by obtaining IDs and passwords of system administrators and altered beneficiary names and account details," said a Calcutta-based web developer.

Opposition parties slammed the ruling Trinamool for "engineering the loot".

“The attempt to frame this as a hacking issue is weak. People in Bengal can see through this — it's yet another instance of organised looting by the ruling party," said BJP spokesperson Samik Bhattacharya.

CPM leader Sujan Chakraborty said: “We suspect TMC leaders are involved in it. The state is trying to hush up the scam by terming it as a cyber crime."

Despite the recent arrests, the trend of siphoning the grant seems to have continued in the districts.

In Howrah, six schools on Thursday reported that funds had been diverted to other accounts and 124 students were deprived. In Cooch Behar, Alokchandra Bhat, the headmaster of RGL High School at Pundibari, said on Thursday that at least 50 students did not receive the grant.

Additional reporting by Soumya De Sarkar in Malda.