LAGUNA BEACH, CA: Apple Pay has become the market-leading mobile payment offering in the US, according to CEO Tim Cook, with more than one million credit card activations within 72 hours of its official launch.

"Visa and MasterCard – we talked to these guys today," he told the Wall Street Journal's WSJDLive Global Technology Conference, "and they told us that if you sum up everyone else that's in contact-less mobile payments at the point of sale, we're already number one."

In addition to Visa and MasterCard, Apple has signed up American Express and other issuers accounting for around 83% of all credit card transactions in the US.

Given that level of engagement, Cook dismissed as a "skirmish" reports that some retailers, including Rite Aid and CVS Health, had refused to accept Apple Pay at their stores.

Wired noted that major retailers had been developing their own mobile payment app, CurrentC, which links to customer accounts and cuts out credit card companies and their fees. But making the app a success could cost more than any savings they might achieve.

"Shutting out Apple and its user experience expertise isn't about doing what's best for customers," it said. "It's about what retailers perceive to be best for their bottom lines."

In any case, Cook was unperturbed. "We have a lot more to go," he said. "We have a lot of merchants to sign up. We have a lot more banks to sign up. And we have the whole rest of the world. We are only in the US right now."

A tantalising glimpse of the possible future direction of Apple Pay came when Jack Ma, CEO of Alibaba, indicated an interest in partnering with Apple Pay.

Alibaba's Alipay service has 300m active users and when asked about a tie-up with Apple Pay, Ma told the conference, "I hope we can do something together". Cook also said he was meeting Ma later this week.

Data sourced from Wall Street Journal, Wired; additional content by Warc staff