Police have stumbled upon a fake credit card, the magnetic strip of which contains all the data of a genuine card issued by a Chinese bank.

Three Bangladeshis, including a woman, were arrested on Thursday in connection with the forgery. The woman, Sultana Begum, was picked up from a jewellery shop in New Market, from where she had bought a gold chain using the fake card.

“This is the first time we are dealing with such a hi-tech forgery,” said Pradip Chatterjee, deputy commissioner of police (headquarters).

Sultana and a male accomplice visited the jewellery shop, B. Motiram, on Thursday night. “They bought a gold chain for Rs 20,500 using the card bearing Sultana’s name and then asked for three more chains, worth Rs 50,000. Despite the costly deal, they did not bargain even once, making the shop-owner suspicious,” said Chatterjee.

He immediately called the police, who got in touch with a private bank whose name was inscribed on the credit card. “Officials from the bank came to the shop and said the card was not issued by them,” said an officer of New Market police station.

The sleuths became sure when the officials entered the card number in a protected website that can be accessed only by banks. “The site showed the card was issued by a Chinese bank to a Chinese national, named Wang Quee Kiong,” said the officer.

Sultana, forced to stay put in the shop, was rounded up, though her accomplice managed to flee. “We raided the central Calcutta hotel where she and her friends had checked in five days ago and arrested Iqbal Khan and Saifur Rehman,” the officer added.

Two passports and another forged credit card were seized from Khan and Rehman, who had travelled to Singapore and Bangkok in the past year.

The sleuths, however, are yet to figure out how the three managed to store all the secret data of a genuine card, including the security code number and the credit limit, in the fake one.