(CNN) - Apple suddenly pulled a popular Bitcoin app out of its mobile marketplace.
The Blockchain app was downloaded 120,000 times during its two years in Apple's iTunes app store.
It was the most popular way for people and companies to transfer Bitcoins to one another.
Apple removed it from the store on Wednesday without explanation.
Blockchain immediately shot back with a statement accusing Apple of getting overly aggressive with future competitors.
Apple is rumored to be developing its own mobile payment system.
Blockchain is still available in the Google Play Store.
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