In China, iPhone owners can now break out their iPhone and Apple Watch to pay for goods by using Apple Pay. Apple Inc. on Thursday officially rolled out the mobile payment system to the country, in partnership with the nation’s only interbank network, China UnionPay.

Customers with eligible debit and credit cards can add their payment cards to their Apple mobile wallet. The iPhone maker launched the service with the support of 12 of China’s banks, such as the Agricultural Bank of China and the Bank of Shanghai. Seven more banks, such as the Bank of Beijing, are expected to support the service later in 2016.

"We think China could be our largest Apple Pay market," Jennifer Bailey, vice president of Apple Pay, told Reuters. China is one of Apple’s largest markets, second only to the the Americas. The region accounted for $18.4 billion in revenue in the December holiday quarter, up 14 percent from the same three-month period in 2014. That’s despite the slowdown of China’s overall smartphone market, which fell to 3.4 percent growth in 2015, down from 33.6 percent in 2014, according to Strategy Analytics.

Apple Pay is available to customers in China with an iPhone 6 or later and the Apple Watch. The service can be used at any retail store in China that has a register compatible with the China UnionPay credit card network and supports contactless payments through near-field communication (NFC) wireless technology.

In addition, customers will also be able to pay for purchases in apps as developers add support for the service.

Apple Pay first launched in the United States in 2014 and has since expanded to the UK, Canada and Australia. Support for the service in Hong Kong, Singapore and Spain is expected sometime later in 2016.