In what could be seen as another blow to the popularity of virtual currency Bitcoin, this week Apple removed Blockchain, the last remaining Bitcoin wallet app available from its App Store, citing an "unresolved issue." According to UK-based Blockchain, it received no prior warning of a problem.

The Blockchain app was added to the App Store in 2012 and was one of the most popular Bitcoin wallet apps. With Blockchain gone, iOS users will no longer be able to access the world's most popular virtual currency, as the iPhone maker has already pulled off other related apps including Coinbase and Gliph.

According to Nicolas Cary, CEO of Blockchain, Apple had previously pulled off the app, but it was later re-accepted. While Cary believes that the removal of the app indicates that the Cupertino-based company sees Bitcoin as a potential competitor, others argue that the decision to dump Bitcoin wallets could be attributed to confusing international regulations surrounding the virtual currency. Blockchain had been downloaded over 120,000 times from the iOS App Store in the past couple of years.

In contrast, Google seems to have no problem with Bitcoin. Hundreds of Bitcoin wallets, including apps from Blockchain and Coinbase are available on Android. “We’re totally cool with Google,” says Cary.

Kyle Drake from Coinpunk has urged users to raise their voice against Apple's move by signing a petition to allow Bitcoin wallets on the iPhone.