A Nigerian who had allegedly duped people by sending them text messages saying their WhatsApp numbers had won a prize and asking them to share their personal details to claim the money, has been arrested in Delhi on Wednesday.

John Effe Simon, 34, was arrested by a team of Calcutta police from Tigri in Delhi after a “hot pursuit” of more than an hour through a crowded neighbourhood where many foreigners stay, police sources said.

“This man is the mastermind of the racket that would send the same message to thousands of people and lure them into sharing their personal details through the e-mail ID mentioned in the text message,” said joint commissioner (crime) Murlidhar Sharma.

The text messages sent to hundreds of people contained an e-mail ID (rbidelhi@ rbigovt.in) to which the recipients were asked to revert with his or her name, address, mobile number and age.

“Once a person shares the details, he or she is told that the prize money could be directly transferred to his or her bank account or could be sent physically. For those who opted for online transfer, the fraudsters would convince the person over the phone to share his or her bank details, including the one-time password,” said an officer.

If someone preferred physical transfer of money, the fraudsters would share a phone number saying it was that of a customs officer dealing with the consignment. The fake customs officer would tell the person to pay a processing fee if he or she wanted to claim the money.

The city police launched a probe after receiving more than a dozen complaints.