Four directors of a call centre in Salt Lake were arrested on Thursday for allegedly duping many people from the UK, Portugal and South Africa in the guise of providing software services.

Police said the accused would coax the victims into installing a software in their computers, which would lead to installation of a spyware that would enable the fraudsters to gain control of the devices.

The men who were arrested were Gurdeep Singh, 45, from Entally; Santosh Kumar Yada, 31, from Behala; and Howrah residents Abraz Ahmed, 30, and Jasim Anwar, 31.

The police said they were part of a group of six who owned the call centre, which functioned from a building in Sector V’s EP-GP block.

“We are looking for the other two men,” said an officer of the cyber crime police station in Salt Lake.

“The call centre had at least 150 employees, who would call up people overseas. Employees of the call centre would call up foreign nationals and dupe them by claiming that they provided solutions to problems related to software and viruses. They used to make VoiP calls using at least 70 computers.”

The employees would convince their victims that they were calling from a software major and offer to resolve problems in their computers at a nominal fee, the officer said. During the course of the conversation, the callers would ask the victims to install a software that in turn would give them remote access to the victim’s computer.

Once they did so, the callers would take over control of their computers. When the victims would try to pay them for their “service”, the callers would enter an amount much higher than the “nominal fee” they had demanded.

Bidhannagar police commissioner Mukesh said they had launched a drive against illegal call centres. “We are making regular arrests. This is part of our drive,” Mukesh said.

The police suspect the gang had duped foreign nationals of crores of rupees. A case has been started under IPC sections related to cheating, fraud, forgery and criminal conspiracy, and also under the Information Technology Act.

Illegal call centres have mushroomed across the city, the police said. Over the past few months, the Bidhannagar commissionerate has arrested many suspects who allegedly cheated people across the globe posing as employees of software giants or promising high returns for a place to install mobile towers.

In most cases, the alleged fraudsters convince their clients to install software in their computers through which they could access the device.