A 68-year-old man was duped out of ₹19.5 lakh after he clicked on an advertisement for a “pension card” on social media.

A man was arrested on Friday morning in connection with the case.

A resident of Garfa Sitala Mandir Road spotted an advertisement on Facebook on February 7 and clicked on it, thinking it would help him get a secure income.

Police said that after Vivekananda Mitra had clicked on the link, he was later contacted by unknown persons through two WhatsApp numbers who introduced themselves as bank officials.

“Acting on their instructions, Mitra downloaded a file on his phone, which we later found was an APK file,” said an officer of Kolkata Police.

A file with an APK (Android Package Kit) extension becomes a malicious link that gives access to the phone on which it is downloaded to the fraudsters who send such files, the police said.

Mitra lost ₹19.5 lakh to the fraudsters.

During their investigation, the police tracked the fraudulent transactions and zeroed in on a person based in Khejuri in East Midnapore as being behind the calls.

The police said Gopal Kamila, 28, was arrested in Khejuri early on Friday morning.

Senior officers said it was always advisable not to click on advertisements on social media, even if they were very tempting.

“Social media platforms do not filter advertisements based on their authenticity. Hence, it is always advisable not to click on any offers, financial scheme advertisements that appear on social media,” said an officer of the detective department of Kolkata Police.