The Financial Conduct Authority said the probe focuses on whether the companies breached the UK’s Competition Act, which prohibits firms from agreeing to conduct that may harm competition.

It is also investigating whether Visa and Mastercard abused their dominant position in the market.

The FCA said “it has reached no conclusions nor made any findings with regard to competition law having been broken.”

All three companies confirmed they are cooperating with the regulator.

PayPal’s digital wallet lets users pay online or in stores using a linked bank card or bank account, without sharing their financial details directly with the seller.

Mastercard said it had received requests from the regulator regarding its “contractual relationship with PayPal.”

Visa said it was aware of the opening of the investigation, which concerns “certain contractual provisions regarding the PayPal digital wallet.”