Sweden's foreign minister has called for Ukraine to act following the exposing of an alleged cryptocurrency fraud operation duping naive investors from the country's capital.

The so-called "fraud factory," working from two floors of plush offices in Kyiv, was exposed after an investigation by Swedish daily Dagens Nyheter (DN) published Monday.

Called Milton Group, the firm was revealed to have employed ranks of telemarketers cold-calling potential investors, often older people, and offering inviting returns on money put into stocks and cryptocurrencies.

However, DN writes in the report: "Their real operation is committing fraud on an industrial level – and their victims are from all around the world."

Responding to the claims on Tuesday, Swedish Foreign Minister Ann Linde said, "It is really upsetting to see how they bluff Swedish retirees who have to leave their homes and live on a minimum subsistence level. And then they sit there, laughing."

As quoted by the Organized Crime and Corruption Reporting Project, Linde added that it's "important" that authorities in Ukraine are informed about Milton Group's alleged activities and that the claims are looked into.

DN alleges a number of individuals have lost their life savings through the scheme. In all, it says that the firm has left possibly 1,000 people from over 50 countries with losses. It's not clear how much money may have been taken by the scheme, but a team member is caught on video boating of persuading one individual to hand over $150,000.

After persuading a victim to part with an initial investment of around $100, DN said, the salesperson then attempts to persuade the victim to install a program said to assist with financial advice. In fact, it provides Milton's staff with full control of the host computer. The claims include that "big" loans were taken out in victims' names without their permission using banking data stolen via the app and ID information that victims were asked to provide.

After initial investments, victims are shown figures suggesting high returns. Yet when they tried to withdraw the funds, the money disappeared, the investigation found. Some have also been left with sizable loans they hadn't agreed to.

The investigation was carried out with the help of a whistle-blower within Milton Group who provided materials from the firm's own database, as well as video recordings of the team's activities.