Iran's attempts at censoring digital communications have come under global scrutiny in recent months, and now the country's supreme leader Ayatollah Ali Khamenei has issued a fatwa outlawing anti-filtering tools that help citizens access blocked material on the internet. However, in an ironic twist, less than 30 hours after being published the religious edict itself was blocked to those trying to access it inside the country. Because the filtering software uses fairly simplistic keyword tools to detect pages which should be banned, it's likely that the occurrence of the word "anti-filtering" was enough to place the site onto the blacklist.

It's the latest in the country's attempts to create a "safe" internet, which blocks content that could present a threat to the government in a style similar to China's firewall. Google has already confirmed that its encrypted services are unavailable to Iranians, a move which also prevents the use of many proxies.