Seven people were arrested in Jamtara, Jharkhand, in the past two days in connection with bank frauds on the phone.

The arrests were made based on the complaints of two Calcuttans who had lost close to Rs10 lakh during the lockdown. They had shared their bank details with callers on the phone who posed as bank officials, police said.

These men usually call up people in Calcutta posing as bank or income tax department officials and persuade such people into sharing their bank details with them, the police said. Once they get hold of the bank details, they transfer money from a victim’s account to multiple e-wallets.

In June, Pratyusha Sinha Basu Mullick, who lives in the Sanjeeva Town Bungalow Complex in the Calcutta Leather Complex area, had reported how she had lost Rs 6 lakh to a caller who had fraudulently obtained her banking details and the one-time-password generated on her phone.

The next month, Ruma Majumdar, a resident of East Bishnupur in North 24-Parganas had reported that Rs 4.63lakh had been withdrawn from her account in the Shyambazar branch of a nationalised bank.

“Both complainants had reported the matter to us as soon as the crime had been committed. So, we were able to block and retain a part of the transferred money,” an officer of the detective department’s anti-bank fraud section said.

As part of the modus operandi, the gang members used to call up people; at times posing as bank officials and telling them that their debit cards were about to be blocked or their e-commerce accounts were about to be invalidated for want of KYC. Some even told people that they had won prizes in reality shows and their bank details were needed to get them the prize money.

The money was transferred from the victim’s bank account to multiple e-wallets to minimise the chance of the money trail getting identified, the police said.

The Telegraph had on August 9 reported how Lalbazar had been flooded with more than 1,700 complaints of bank fraud, amounting to more than Rs3 crore. Of that at least 1,600 were connected to Jamtara.

In several cases, cops found that the phone numbers that had been used to contact the complainants had SIM cards bought from Bengal.

“That was the first time we found a direct link between the Jamtara gang and Bengal. SIM cards had been bought from Malda, Nadia and pockets of South 24-Parganas close to Calcutta,” an officer said.

The number of complaints in June and July had shot up as a several people, especially the elderly, who were otherwise uncomfortable with online transactions had to go online to clear various dues during the lockdown, the police said.

The city police have been running a helpline (8585063104) for people to report bank frauds on the phone.