Geneva, Switzerland - UN-mandated investigators probing rights abuses in Iran said Wednesday they were appalled by the deadly strikes targeting the country's officials, saying extrajudicial killings were no way to deliver justice.

The United Nations' Independent International Fact-Finding Mission on Iran said it strongly condemned the US-Israeli attacks on the country, which began on Saturday.

The probe said it was "appalled" that dozens of Iranian officials have been killed in targeted US-Israeli air strikes.

"Even if some of these individuals may have borne responsibility for human rights violations or international crimes, extrajudicial deprivations of life are not an acceptable means for delivering justice under international law," it said.

The rules of international law "cannot be varied according to the state taking action", the investigators said.

Iranians now find themselves trapped in a grim situation, said the mission.

"The Iranian population is now caught between a large-scale military campaign that may go on for weeks or months, and a government with a long record of gross human rights violations," it said.

The investigators urged Tehran to stop its latest telecoms and internet blackout.

"The shutdown has cut off the Iranian people from the outside world, denying them access to crucial information on nationwide attacks or contact with loved ones," they said.

The three-person mission is tasked with gathering and preserving evidence of rights violations in Iran.

The UN Human Rights Council created the high-level investigation into ongoing serious rights violations in Iran in November 2022, shocked by the deadly crackdown on widespread demonstrations sparked by the death of Mahsa Amini.

The probe also raised concerns for Iran's prison population, including the "tens of thousands" detained over the renewed mass protests that broke out on December 28.

"It is critical that military attacks – such as those on Evin Prison in Tehran by the Israeli military on June 23, 2025 – are not repeated at this time, with obvious risks to detained protesters and other civilians," it said.

The investigation called for evidence to be gathered and secured on civilian casualties of the war, so that those responsible may be held accountable.

"All those with influence need to act urgently to put an end to this war," it said.