Internet censorship in countries in the Middle East and North Africa is on the rise, according to a new report published by the OpenNet Initiative, a non-partisan group that monitors Internet filtering and surveillance practices.

Researchers at the OpenNet Initiative reported that Middle East and North Africa are among the most heavily censored regions in the world. The group indicated that "Internet censorship system in Iran is one of the most comprehensive and sophisticated in the world."

According to the report, "Internet censorship in the region is increasing in both scope and depth, and filtering of political content continues to be the common denominator among filtering regimes there," said Helmi Noman, the OpenNet Initiative's Middle East and North Africa lead researcher, in the report published Wednesday.

"Governments also continue to disguise their political filtering, while acknowledging blocking of social content, and censors are catching up with increasing amounts of online content, in part by using filtering software developed by companies in the U.S."

The report found that 14 out of 18 countries in the Middle East and North Africa filter Internet content.

It also found that political censorship is being applied to more content and is becoming more consistent. Countries that regularly filter political content are also increasingly adding social networking and other Web sites such as YouTube, Facebook and Amazon to their blacklists.

Many countries in the region also censored sites that present critical reviews of Islam or attempt to convert Muslims to other religions.

Despite the increase in censorship and content filtering, there have been few examples of unblocking sites to which access had been previously denied. Syria, for example, recently restored access to Wikipedia Arabic and Libya has also allowed access to some previously banned political sites.