France, Jan. 12 -- The blackout is making it far harder for protesters to communicate and for images and eyewitness accounts to reach the outside world. It has also disrupted daily life in Iran, where banking, payments and many basic services rely on digital networks.

For more than two and a half days, Iran has been largely cut off from the outside world and from itself. The flow of information inside the country and abroad has slowed to a trickle, with most Iranian websites inaccessible from outside Iran.

The nationwide shutdown began late on Thursday and quickly spread across the country. The independent monitoring group NetBlocks said the blackout had lasted for more than 60 hours, with national connectivity stuck at around 1 percent...