Five unlicensed money changers were Tuesday arrested in Gisenyi Sector, Rubavu District in the latest crackdown on illegal currency trading.
Speculators and illegal money changers have often been blamed for the volatility in the currency market.
Police spokesperson for the Western region, Chief Inspector of Police Innocent Gasasira, said that the suspects, all women, were "arrested red-handed exchanging money at Petite Barrière border post with Democratic Republic of Congo.
One of the suspects is a minor, he said.
"They were found with varied amounts of money in different currencies, including Rwanda and Congolese francs, and US dollars. The suspects and exhibits have since been handed over to Rwanda Investigation Bureau in Gisenyi," he said.
Economists say that unlawful financial businesses could distort the forex market, trigger dollarisation of the economy, fuel inflation and reduce the competiveness of local products in the international market.
According to central bank regulations, no individual or company is allowed to trade in currencies without a license.
Gasasira said that; "There is a proper and legal way through which money exchange business is conducted; because they know what they are doing is illegal they tend to employ varied tricks to run their black market,"
He added: "This is why the Police normally conducts targeted operations based on credible information on specific people involved and their bases."