EU antitrust regulators are seeking more information on Apple's mobile payment system, the European Commission has signed that the enforcer is looking to close any loopholes and boost its case against the iPhone maker.

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.

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.

Norwegian mobile payment app and complainant Vipps said, however, that alternatives to NFC are cumbersome and not competitive.

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.

The regulator, that makes Apple up to 10 percent of its global turnover if found guilty of breaching antitrust rules, typically issues decisions after the hearings.

Recently, Apple was planning to unveil its first mixed-reality headset this year after postponing the launch of its augmented reality glasses indefinitely due to technical challenges, according to a report in tech publication The Information.

The company is focusing on the lower-cost mixed-reality headset market to reach more people instead of the AR glasses, which were planned to be released in 2024. Apple’s mixed-reality headset, will use displays and pass-through cameras to create an immersive AR-VR environment.