PARIS, France (AFP) — Protests in Iran have subsided after a crackdown that has killed thousands under an internet blackout, monitors said Friday, a week after the start of the largest demonstrations in years challenging the country’s theocratic system.

Reza Pahlavi, the United States-based son of Iran’s late shah, however, said he was confident the Islamic republic would fall and called for intervention, though the threat of new military action by the US against Iran has appeared to have receded for the time being.

In posts to social media on Friday, Pahlavi announced a fresh coordinated demonstration, calling for Iranians to “raise your voices in anger and protest with our national slogans” on the weekend.

Protests sparked by economic grievances started with a shutdown in the Tehran bazaar on 28 December but turned into a mass movement demanding the removal of the clerical system that has ruled Iran since the 1979 revolution.

People started pouring into the streets in big cities from 8 January but authorities immediately enforced a shutdown of the internet that has lasted over a week and activists say is aimed at masking the scale of the crackdown.

The “brutal” repression has “likely suppressed the protest movement for now,” said the US-based Institute for the Study of War, which has monitored the protest activity.

But it added: “The regime’s widespread mobilization of security forces is unsustainable, however, which makes it possible that protests could resume.”

Pahlavi also told a news conference in Washington on Friday that “The Islamic republic will fall — not if, but when.”

“I will return to Iran,” he said.

Norway-based rights group Iran Human Rights (IHR) says 3,428 protesters have been verified to have been killed by security forces, but warns the actual toll could be several times higher.

Other estimates place the death toll at more than 5,000 — and possibly as high as 20,000 — with the internet blackout severely hampering independent verification, IHR said.