The US has accused Iran of seeking a "near-total information blockade" to silence anti-government protesters. The allegations came after opposition supporters clashed with security forces as Iran marked the anniversary of the 1979 revolution. <br/><br/>The US government said it had information that the telephone network was taken down, SMS messages blocked, and internet communication "throttled". China and Burma have also been accused of blocking internet communication. Analysts say, some governments make strenuous efforts to block modern communications among opponents, with varying degrees of success.