IPF was already overhauling its fees and products in Poland to meet an August 1 deadline and avoid a fine from the Office of Consumer Protection and Competition. The firm said it will reform its loans to mitigate the effects of the rule change.

“Dependent on legal interpretation of the final version, however, there can be no assurance that the legislation, if introduced in its present form, would not have some adverse financial impact on IPF,” the company said.

Interest rates on loans in Poland are already capped at four times the Lombard rate, which is set by the central bank and is currently 2.5pc.

The proposed reforms would also cap penalty interest, and limit all non-interest costs, such as arrangement fees, to no more than 25pc of the original loan plus 30pc a year, with an overall limit of 100pc. An earlier draft of the reforms only affected certain mandatory charges.

Shares in IPF fell 12.6pc to 412p in early trading. The stock is now lower than it was in December 2013, when the firm was subject to an earlier penalty in Poland.

IPF does not lend in Britain, where short-term credit providers have been subject to a price cap since the start of the year. Wonga and other credit firms best known for high-interest payday loans are broadening their products to offer loans over a longer period.

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