According to a new report, EU antitrust regulators are seeking more information on Apple's mobile payment system, the European Commission said on Wednesday, a sign that the enforcer is looking to close any loopholes and boost its case against the iPhone maker.

Reuters notes that "The EU competition watchdog last year accused Apple of restricting rivals' access to its tap-and-go technology, Near-Field Communication (NFC), used for mobile wallets, making it difficult for them to develop rival services on Apple devices.

"We can confirm the sending of requests for information," a commission spokesperson said, while declining to provide details.

Apple has previously pointed to PayPal's success on its iOS mobile operating system as an option for users as well as competition from Danish rival MobilePay, Sweden's Swish and Belgium's Payconiq.

The commission's request for information to rivals and retailers is unusual as it comes three months after Apple defended itself at a Feb. 14 hearing."