Iranian Labour News Agency (ILNA) reported that Iran's government has shut down access to Facebook in the run-up to the country's elections in June.
The report said, "according to certain Internet surfers, the site was banned because supporters of Mir Hossein Mousavi were using Facebook to better disseminate the candidate's positions."
Iran's last prime minister when the position was abolished in 1989, Mr Mousavi is considered a front runner to replace President Ahmadinejad in the June 12 elections, according to the BBC, which said his Facebook page has more than 5,000 supporters.
Juan Cole, writing in his bog on Middle Eastern affairs Informed Comment (which is also blocked in Iran) observed, "The smart thing to do would have been to encourage the other candidates also to use Facebook, thus levelling the playing field."
He added, "Authoritarian regimes cannot imagine that everyone benefits from more peaceful political competition."Facebook reportedly expressed disappointment upon hearing that Iran has blocked it.