The Dutch competition regulator has opened an investigation into contactless payments on smartphones, arguing that some systems could stifle innovation in the payments market. There’s no named target for the probe, as per the watchdog’s usual procedures, but the release suggests Apple and its iPhones are the focus.

Banks and financial technology companies have long complained that only the Apple Pay digital wallet is allowed to access iPhones’ NFC chips for the purpose of contactless payments. “NFC” refers to near-field communication, the wireless technology that enables people to pay for things by tapping a card or a phone on a reader.

This stops rival payments companies from establishing their own lucrative digital wallets in Apple’s ecosystem. The Android ecosystem, by contrast, allows NFC payments with wallets other than its own.

“This problem may stifle innovation with respect to payment apps, and it reduces the freedom of choice for consumers and businesses,” the Netherlands Authority for Consumers and Markets (ACM) said in a Friday statement.

The ACM noted that there is an EU-wide financial regulation that says consumers should be able to choose their method of payment at a brick-and-mortar store.

Then there’s the question of whether Apple’s stance violates EU competition law. The European Commission in June opened a formal antitrust probe into this question and others involving Apple Pay.

“ACM will investigate whether limiting the payment apps’ access to NFC communication reduces the users’ freedom of choice,” the Dutch watchdog said Friday. “ACM may also come to the conclusion that these rules have not been violated. In that case, the investigation will be terminated. If ACM does establish a violation, it may result in a penalty, such as a fine.”

However, the regulator told Fortune the main aim of the investigation was to ensure “other payment apps will also be able to gain access to NFC.”

Responding to a request for comment, Apple did not directly refer to the Dutch investigation but instead said Apple competes “every day—working with banks, fintechs, and merchants to be the best payment option for business and consumers across the Netherlands.”

Apple has previously argued that its NFC limitations are a necessary security measure; the financial companies disagree.