Internet services that enable individuals to freely access blocked sites and programs from within China have seen serious disruptions said moves that Chinese state media said were warranted, three suppliers.

“This week’s assault on VPNs that influenced us and other VPN suppliers is more complex than that which we have found before,” said Sunday Yokubaitis, president of Golden Frog.

Blocks and strikes on foreign internet services are now increasingly common in China. Censors keep a tight grasp on what can and can’t be printed on the internet to remove anything viewed as a danger to the ruling Communist Party.

VPNs enable businesses and people to get sites and services which are usually blocked in China, including those managed by Facebook Inc Google Inc and Twitter Inc.

Several national firms in China and nearly all foreign use VPNs to run company unimpeded by disruptions to web services. People lately widely us the services which have found interruptions, mostly changing cellular devices.

StrongVPN said on its website that a number of its own servers weren’t working for users in China. Golden Frog, which runs the service VyprVPN, additionally reported heightened disruptions in recent days that were past.

Hua Chunying, a spokeswoman for China’s Foreign Ministry, said she wasn’t alert to the details and had not seen reports associated with the VPN disruptions.