A boom in lending by financial technology (fintech) firms in Kenya has led to an increase in predatory lending practices, the country’s central bank governor said on Tuesday, calling for the sector to be regulated.

Kenya built a reputation as a pioneer of financial inclusion through its early adoption of a mobile money system that enables people to transfer cash and make payments on cellphones without a bank account.

More than 20 companies are using the same technology to extend credit to the banked and unbanked alike, saddling borrowers with high interest rates and leaving regulators scrambling to keep up.

From having little or no access to credit, many Kenyans now find they can get loans in minutes.

“There’s an increase in let’s say financial-type institutions that are taking advantage of our population,” Patrick Njoroge told executives in the digital financial services industry at a conference in Nairobi.

“In a sense what has happened is there is an opportunity by some predators and they are preying on our population.”

In the last three years, 2.7 million people out of a population of around 45 million have been negatively listed on Kenya’s Credit Reference Bureaux, according to a study by Microsave, a consultancy that advises lenders on sustainable financial services.

As it was for mobile cash, Kenya is considered a test case for the new lending platforms. Several of the companies involved, including U.S. fintech startups, have plans to expand in other frontier markets, meaning Kenya’s regulation will be closely watched.

Njoroge said he did not like the idea of his country being a “guinea pig” for new technology deployed by foreign companies.

“What I think is worrisome is a lot of products that are coming in a sort of a fly-by-night operation and you only hear about it because somebody gets burned,” he said.

He said the risks to Kenyans showed there was a need for regulation in the booming sector.

A draft bill published by the finance ministry last week for review and comment by the public and industry says digital lenders will be licensed by a new Financial Markets Conduct Authority and lenders will be bound by any interest rate caps the Authority sets.

But it is not clear if digital lenders are subject to the current government cap on banks’ interest rates which has slowed private sector credit growth since it was introduced in 2016.

Njoroge did not comment on whether the draft bill would serve as an adequate check on predatory lending. “That’s for you to judge,” he said.