WHEN thousands of protestors took to the streets in Iran following this year's disputed presidential election, Twitter messages sent by activists let the world know about the brutal policing that followed. A few months earlier, campaigners in Moldova used Facebook to organise protests against the country's communist government, and elsewhere too the internet is playing an increasing role in political dissent.
Now governments are trying to regain control. By reinforcing their efforts to monitor activity online, they hope to deprive dissenters of information and the ability to communicate.
The latest evidence of these clampdowns comes in a report on the Middle East and north Africa by the OpenNet Initiative (ONI), a collaboration of researchers based in the UK and North America."Political filtering is the common denominator," says Helmi Noman of the Berkman Center for Internet and Society in Boston, who compiled the report. "It's the main target."
Monitoring has become more widespread as the internet's role in political activity has increased
In western democracies, censorship is aimed mainly at sites offering child pornography or images of extreme violence.
China has developed an extensive system of filters which it uses to block access to content about sensitive topics, such as the protests in 1989 in Tiananamen Square, Beijing. Other Asian nations, including Thailand and Vietnam, have taken action against blogs and news sites that host material critical of their leaders. More
