Fraudsters might actually have stolen over Tk 1 crore -- four times the amount initially thought -- from ATM booths of several banks using cloned cards last month, the central bank and investigators say.

Only three banks were previously said to have been hit by the fraudulence between February 6 and 12. They are City Bank, Eastern Bank (EBL) and United Commercial Bank (UCB). But it is now understood that more banks have been affected.  

The latest addition to the list is Premier Bank, from where a gang pocketed Tk 40 lakh by cloning credit cards issued by Al Rajhi Bank of Saudi Arabia, sources said. 

“There are more banks that have fallen victim to the recent card frauds,” Shubhankar Saha, executive director and spokesman for Bangladesh Bank, told The Daily Star on Thursday.

He declined to give the number or names of the affected banks, citing the ongoing investigation by the central bank.

Police have so far arrested four people in this connection -- one Ukraine-born German national and three officials of City Bank's card division.

It is believed that fraudsters stole data of around 7,000 cards used in four ATMs of City Bank, EBL and UCB in Dhaka early last month. Initial probe found they were able to use only 40 cards and withdraw about Tk 25 lakh, before it was discovered on February 13. 

Then last week, the biggest yet forgery was detected involving the withdrawal of Tk 40 lakh from Premier Bank using five international credit cards of the Riyadh-based bank.

Another two such cards got stuck in the machines and the gang failed to steal any cash using those. 

The cards were used on last Saturday and Sunday, said Khondker Fazle Rashid, managing director of Premier Bank. The bank filed a case with Banani Police Station and informed the BB about it on Monday.

With the latest detection, the amount stolen so far stands at Tk 65 lakh. But it would go up once the BB gets information from all the banks hit by the trickery, said the BB executive director.

Another BB official fears the same. “We don't know exactly how many cards have been cloned by the gang. These cards could be used later inside and outside the country,” said the official.

“We don't know whether these cloned cards have already been used in foreign countries,” he added, asking not to be named.

“Along with local cards, foreign cards were also used in ATMs that were skimmed off recently. After cloning these cards, fraudsters will use international cards in foreign countries,” said Kazi Saifuddin Munir, managing director of IT Consultants that runs Q Cash, an electronic payment switch.

For years, skimming has been a popular technique used by fraudsters across the world. They steal data from the card's magnetic stripe with a device hidden near the ATMs' card slots.

To get the card's personal identification number (PIN), an overlay is placed over the ATM's PIN pad or a concealed camera is used.

Meanwhile, the ATM fraudulence has been affecting both the industry and customers, with banks fearing to lose money as card users lose their confidence in the system.