Information on Apple Pay is being sought by EU antitrust investigators.

(Reuters) – BRUSSELS The European Commission said on Wednesday that EU antitrust officials are seeking additional information on Apple’s (AAPL.O) mobile payment system in an effort to shut any loopholes and strengthen its case against the iPhone manufacturer.

Last year, the EU’s competition authority accused Apple of limiting competitors’ access to its tap-and-go technology, Near-Field Communication (NFC), used for mobile payments.

A representative for the commission stated, “We can confirm the sending of requests for information,” but they would not elaborate.

However, Apple refused to provide a statement.

Apple has previously mentioned PayPal’s (PYPL.O) popularity on iOS as an example of an alternative for consumers, along with the successes of Danish competitor MobilePay, Swedish rival Swish, and Belgian rival Payconiq.

Complainant Vipps, a Norwegian mobile payment app, said that NFC’s alternatives are too inconvenient to be competitive.

Three months after Apple defended itself in a hearing on February 14, the commission has made an unprecedented request for information to competitors and merchants.

After hearings of this kind, the regulator routinely makes rulings carrying fines of up to 10% of Apple’s worldwide revenue for violations of antitrust regulations.