Bangladesh, Feb. 25 -- A leading international watchdog has sounded the alarm over what it describes as a sweeping campaign of arbitrary arrests and violent repression in Iran, accusing authorities of entrenching a system of impunity to silence dissent and intimidate the population.

In a statement issued on February 24, Human Rights Watch said Iranian authorities have arrested tens of thousands of people since late December in what it characterized as a “brutal campaign” of mass detention. The group alleges that the arrests, carried out by the powerful Islamic Revolutionary Guard Corps (IRGC) and other security forces, are aimed at terrorizing the public and suppressing further protests.

The unrest erupted in late December a...