MUMBAI: A 70-year-old doctor was cheated by cyber criminals of Rs 3 crore and kept under "digital arrest" for eight days after being accused of involvement in a non-existent money laundering scam, a Mumbai police official said on Saturday.

In the month of May, the victim got a call from a person identifying himself as telecom department staffer Amit Kumar, who told her a SIM card had been bought with her personal details for use in criminal activities.

"She then got a call from another person who identified himself as Crime Branch officer Samadhan Pawar. He told the victim that her bank account and debit card details were found in a raid at the residence of an airline company owner who was earlier arrested for money laundering and is currently out on medical bail," the official said.

The accused sent her multiple documents claiming these were from probe agencies like CBI, Enforcement Directorate as well as the RBI.

"A man in police uniform also spoke to her husband on video call, all of which convinced her about the case. She was then put under video surveillance, which these fraudsters call digital arrest, for eight days. She was made to report to them every hour during this period. Out of fear, she transferred Rs 3 crore into various bank accounts given to her," he said.

She approached West Region cyber police station on June 5, after which a case was registered, the official said.

A probe has found the accused converted Rs 82 lakh in cryptocurrency, he said, adding efforts were on to nab them and retrieve the lost money.