Iran has shut down mobile Internet access to overseas sites in several provinces, a day before possible protests.
Iran’s semi-official news agency, ILNA, reported that the shutdown on December 25 was ordered by "security authorities,” quoting a source at the country’s Communications and Information Technology Ministry.
According to the source, the shutdown covered the Alborz, Kurdestan, and Zanjan provinces in central and western Iran and Fars in the south.
"According to this source, it is possible that more provinces will be affected by the shutdown of mobile international connectivity," the news agency said.
NetBlocks, a website that monitors international Internet outages, also reported the disruptions, tweeting that there had been "evidence of mobile Internet disruption in parts of Iran" since 6:30 a.m. local time.
"Real-time network data show two distinct drops in connectivity this morning amid reports of regional outages; incident ongoing."
The disruption comes as social media posts and some relatives of people killed in unrest in November over gasoline price hikes called for renewed protests and commemoration ceremonies for the dead on December 26.
The state crackdown on the rallies last month is thought to have been the most violent response to protests in the 40-year history of the theocratic regime that arose after Iran's 1979 Islamic Revolution.
Officials in Iran have failed to issue a death toll for the deadly unrest while dismissing figures by international rights groups and others as exaggerated.
Amnesty International has said at least 304 people were killed in the nationwide rallies.
Internet access was shut down all over the country for days at the height of the unrest, but images were smuggled out of the fatalities and scenes of violence.
Iranian officials have accused "thugs" connected to "enemies" abroad and the United States, Israel, and Saudi Arabia of involvement in the protests.
Iran's economy and its currency have tumbled since U.S. President Donald Trump withdrew from a 2015 nuclear agreement trading curbs on Tehran's nuclear activities for relief from international sanctions.
Trump's administration has pursued what some U.S. officials have described as a "maximum pressure" policy to force a change of behavior from Iranian officials or to get them back to the negotiating table.