The controversial “Golden Passport” (or visa) is back in the spotlight after a leading London firm opened up about the “huge increase” in demand for its services. The EU Commission has told EU states to tighten checks on non-EU nationals who acquire citizenship via these “golden passports” in exchange for big investments as it can be abused for tax evasion and money-laundering.

Nonetheless, Luke Hexter, managing director of Knightsbridge Capital Partners, told Forbes that their European Passport program was driving 70% year-on-year growth at the firm. This comes after Knightsbridge was involved in a Sunday Times and Channel Four investigation which discovered the firms brokering U.K. investment visas and European passports for foreign billionaires and millionaires had been boasting about their ability to sidestep government checks and safeguards for their clients.

Knightsbridge currently sells passports from Cyprus, though Malta and Bulgaria also provide passports to non-EU nationals who make sufficient investments in their countries. These ‘Golden Passports’ give foreign investors and their families the right to travel visa-free to 163 countries, in return for a $2.2 million (€2 million) investment into local property or funds.

The island gained $7.4 billion (€6.6 billion) from selling passports, however the scheme has also attracted the ire of the European Commission and OECD as the Commission believes there is not enough information regarding how the scheme actually works.

Despite the Commissions concerns, the economic growth and political instability in emerging markets has created demand for Golden Passport investment programs, according to Hexter. “If you got a few billion–a lot of these clients will have citizenship in one country, passports in another and residency somewhere else as a way to mitigate risk,” he says.

“Nigeria is a prime example of a country where a lot of people are becoming very wealthy quite quickly. But with the political instability, they still love their country … they just still need to have a contingency plan in place,” he added.

When asked whether the Golden Passport industry and his firm helped criminals to flee justice and hide their ill-gotten gains, Hexter turned to a defensive tone, saying the industry can “get a little bit of flack for pandering to certain unscrupulous high-net-worth individuals,” and that the accusation is “as far away from the truth as can be possible.”

According to Hexter, Knightsbridge Capital “wouldn’t touch a politically exposed person or someone where there’s even a question that their wealth could have been obtained illegally.”

However, this is where the controversy comes into play. For those who are fighting global corruption, these citizen by investment schemes are not as agreeable as the London firms involved would make it out to be. Ben Cowdock, senior research officer at Transparency International, has challenged whether British and European money laundering and background checks are effective in identifying corrupt business leaders and politicians.

The Sunday Times and Channel Four undercover investigation revealed how London’s private client professionalstalked of securing a golden visa for a member of the former Libyan dictator Colonel Gaddafi’s family, in addition to questionable applicants from Thailand, Egypt and Angola. An immigration specialist was also caught on film dismissing Home Office anti-corruption checks as “easy-peasy,” in which the specialist claimed that the officials responsible relied solely on just Googling names.

“Our research has found all too often firms and professionals unwittingly or knowingly offering services to high-risk individuals, enabling them to launder both their money and reputations,” Cowdock told Forbes. He added that more often than not, citizenship is sought by those who benefit from political connections in unstable countries who often need “to escape and enjoy the proceeds of their corruption should they find themselves out of favour.”

According to Cowdock, a British passport is still seen as a public “hallmark of credibility,” in which he warns that the poor quality of checks carried out on those using these schemes allows them to invest funds from questionable origins in addition to “laundering their reputations.”