Iranian blogosphere backs Mousavi as protests mount

According to Internet censorship monitor OpenNet Initiative, Iranians began taking to the Internet in droves during the 1997-2005 presidency of Mohammad Khatami, when dozens of independent publications were shut down and journalists jailed.

In a 2007 report on Iran, the OpenNet Initiative estimated there were about 400,000 blogs in Farsi, as publishing on the Internet exploded, despite what it called "one of the most extensive technical filtering systems in the world."

More than 23 million Iranians in a country of 70 million -- more than 60 percent of whom are under the age of 20 -- have access to the Internet.

Facebook was shut off in Iran on May 23, joining political and human-rights websites which had already been blocked. The ban was lifted on May 26, following strong criticism from moderate candidates.

Mousavi has almost 48,000 supporters on his main Facebook page. Ahmadinejad also has a page with 2,615 fans, while the "I bet I can find 1,000,000 people who dislike Mahmoud Ahmadinejad!" group has more than 57,000 members.

(Editing by Giles Elgood)