China's crackdown on virtual private networks (VPNs) has pushed Apple to remove some VPN apps from the China App Store.

The ExpressVPN iOS app was nixed from the store, the company said in a Sunday blog post.

Noting that “preliminary research indicates that all major VPN apps for iOS have been removed,” ExpressVPN called Apple's decision “surprising and unfortunate” and an affront to free speech.

“We're disappointed in this development, as it represents the most drastic measure the Chinese government has taken to block the use of VPNs to date, and we are troubled to see Apple aiding China's censorship efforts,” the company wrote. “ExpressVPN strongly condemns these measures, which threaten free speech and civil liberties.”

ExpressVPN said that users in China whose billing address is located outside of China can still download the iOS app. Apps for other platforms, such as Windows, Mac, Android, are not affected.

Apple's decision came just as Russian President Vladmir Putin signed a law banning VPNs and anonymizers.