Just over a month into the war, United Nations rights chief Volker Turk warned that governments have dramatically tightened security and restrictions on people's actions and movements in public spaces, infringing on their rights.

"Waves of arrests and broad clampdowns, mostly on vaguely defined accusations, have had a deeply chilling effect on people, many of whom are already living with uncertainty, fear and anxiety," he warned in a statement.

The conflict began when the United States and Israel on February 28 launched airstrikes across Iran, and quickly mushroomed into a regional war.

Turk highlighted estimates that 2,345 people had been arrested in Iran since the start of the war on charges related to national security.

Many of those arrested during mass protests in January and during the ongoing conflict were being held in "shocking conditions" and at risk of being sentenced to death, his office said.

Eight executions have already reported, including three related to the protests, it said, warning that dozens of others who have been convicted, including children.

- 'Outrageous' -

"This is outrageous," Turk said.

"As if the pain and suffering brought on by the war is not enough, some Iranians are being arbitrarily rounded up, jailed, prosecuted without due process, and in some cases then even executed by their own Government," he said, demanding that "all executions must be halted immediately".

The clampdown on rights was not limited to Iran.

His office has received "disturbing reports of arbitrary detentions" and rights infringment from across the region.

"We fear vague security claims related to this conflict are being used instead to further repress and violate people's fundamental human rights - often members of minorities, and those already marginalised."

The rights chief listed a long line of examples, including Israeli authorities detention of 200 Palestinians between February 28 and March 6, including for posting on social media and on suspicion of "glorification of the enemy".

His office also pointed to the death in custody of Shia activist Mohamed Almosawi in Bahrain and mass arrests in Qatar and the United Arab Emirates linked to filming and sharing information.

It also highlighted detentions and law changes in Jordan and Kuwait.

The rights chief also denounced "attempts to limit media freedom" by some countries, pointing to "restrictions imposed by Israeli military censorship authorities, and a threat by the US Federal Communications Commission to revoke broadcast licences for coverage deemed critical of the war".

"Full respect for media independence and freedoms are all the more important in such circumstances, as fundamental to holding governments to public account," Turk said.

"The exercise of such rights must be protected, not threatened."