Apple's CEO Tim Cook said that Apple Pay is growing faster than PayPal when it comes to adding new users and growing the number of transactions.

Cook said that Apple Pay is now completing nearly one billion transactions per month, which is more than twice the volume of a year ago.

Apple Pay has become a popular form of payment in recent years, especially in the US where it is accepted at around 65% of all retailers. It will soon be compatible with several public transit systems, including New York and Chicago.

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Apple Pay is growing at a faster rate than PayPal, according to Apple's CEO Tim Cook.

In a call with investors on Tuesday, Cook discussed the progress of Apple Pay – Apple's digital wallet that lets people make payments with their iPhone – during its most recent quarterly results.

Cook said that Apple Pay is now completing nearly one billion transactions per month, which is more than twice the volume of a year ago. In the past three months, it has launched in 17 new countries, which means its reach now extends to 47 markets in total, including the entire European Union.

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Cook also commented on how Apple Pay stacks up compared to its competitors. He said that during the most recent quarter, it had outpaced PayPal in both the number of transactions per month and the number of new users added.

Cook was likely referencing numbers reported earlier this month in PayPal's second-quarter earnings. PayPal said that it added nine million new members during the second quarter. It also said that engagement per active account increased by 9% to 39 times a year.

Cook didn't disclose Apple's equivalent numbers and a spokesperson did not respond to Business Insider's request for further comment. But his remarks indicate that Apple Pay added at least nine million new users during the quarter.

Apple Pay has become a popular form of payment in recent years, especially in the US where it is accepted at around 65% of all retailers. By the fall, it will also be compatible with several public transit systems, including New York and Chicago. However, it's also a newer payment system and therefore has more room to grow than its more established rival PayPal.