The deadly bombing of an Iranian school spurred "visceral horror", the United Nations High Commissioner for Human Rights has said, urging the US to conclude its probe and demanding justice "for the terrible harm done".
Speaking at the start of an urgent debate in the UN Human Rights Council focused on the 28 February strike on an Iranian elementary school in Minab on the first day of the Middle East war, Mr Turk said that "whatever differences countries have, we can all agree they will not be solved by killing schoolchildren".
The bombing "evoked a visceral horror", Mr Turk told the United Nations' top rights body.
"The images of bombed-out classrooms and grieving parents showed clearly who pays the highest price for war: civilians with no power in the decisions that led to conflict," he said.
"In this case, a reported 168 pupils, teachers, school staff, and their loved ones."
A US Tomahawk cruise missile hit the school due to a targeting mistake, according to the preliminary findings of a US military investigation reported by The New York Times.
Mr Volker stressed that "the onus is on those who carried out the attack to investigate it promptly, impartially, transparently and thoroughly".
"Senior US officials have said the strike is under investigation," he said, calling "for that process to be concluded as soon as possible, and for its findings to be made public".
"There must be justice for the terrible harm done."
The council's discussion, at the request of Iran, China and Cuba, marked the second urgent debate before it this week, focused on the war in the Middle East.
On Wednesday, a debate requested by Bahrain on behalf of the Gulf Cooperation Council and Jordan, considered Iran's strikes on countries across the Gulf region and their impact on civilians.
Following that debate, the 47-member council approved by consensus a resolution condemning Iran's "egregious attacks" on its Gulf neighbours, calling for swift "reparation" to all victims of its strikes.
The council was not asked to consider a draft resolution during today's debate, which was scheduled to last around two hours.
Trump extends deadline for striking Iran's energy plants
Meanwhile, US President Donald Trump has pushed back his deadline for strikes on Iran's energy assets, saying talks on ending the war were "going very well" as Israel announced fresh strikes on Tehran.
The four-week war has spread across the Middle East killing thousands of people and hitting the global economy with soaring energy prices, fuelling global inflation fears.
The United States and Israel launched strikes on Iran on 28 February after talks about Tehran's nuclear programme failed to yield a deal.
US Secretary of State Marco Rubio said G7 nations should help push for the reopening of the crucial Strait of Hormuz, in remarks before arriving in France this morning for a meeting of the bloc's foreign ministers.
Yesterday, Mr Trump threatened during a cabinet meeting at the White House to increase pressure on Iran if it did not make a deal.
He later posted on social media that he would pause threatened attacks on Iranian energy plants for ten days until 6 April.
"Talks are ongoing and, despite erroneous statements to the contrary by the Fake News Media, and others, they are going very well," he added in his Truth Social post.
Around a fifth of global crude oil and liquefied natural gas passes through the Strait of Hormuz in peacetime.
Iran has said it is not engaged in talks with the US and Mr Trump has not identified who the US is negotiating with in Iran, with many high-ranking officials killed in the war.
On 23 March, Mr Trump announced a halt to all threatened strikes against power plants and energy infrastructure for a five-day period, but has now extended it to ten days.
Iran did not ask for a ten-day pause on such strikes, the Wall Street Journal cited peace talk mediators as saying.
Mr Trump told Fox News' The Five programme that the Iranians had asked for a seven-day pause on strikes on energy plants. There was no immediate reaction from Tehran.
Iran has said it would return strikes on energy facilities in the Gulf region if Mr Trump follows through with his threat.
The prospect of tit-for-tat strikes on civilian infrastructure could further rattle global markets and threaten the livelihoods of millions of civilians in the region who rely on electricity to power their cities and supply fresh water.
The war has massively disrupted shipping, sending crude oil prices up around 40%, seen liquefied natural gas prices spike, and prices for nitrogen-based fertilisers, critical to food production, rise around 50%.
Stock indexes fell sharply yesterday, with the Nasdaq dropping more than 2% to confirm a correction, and Brent oil jumped to more than $105 a barrel as hopes diminished for a quick resolution to the war.
Despite Mr Trump's upbeat assessment, Iran continued to retaliate against US and Israeli strikes by hitting Israel and US bases. It also struck Gulf states and effectively blocked Middle East fuel exports via the Strait of Hormuz, which carries about 20% of global oil and liquefied natural gas.
Mr Trump suggested yesterday that Iran let ten oil tankers transit the strait as a goodwill gesture in negotiations, including some Pakistan-flagged vessels.
Mr Trump said the US would become the Iran's "worst nightmare" if it did not comply with US demands, which include opening the Strait of Hormuz and ending its nuclear programme. He said taking control of Iran's oil was an option, but gave no details.
The Pentagon was looking at sending up to 10,000 additional ground troops to the Middle East, the Wall Street Journal reported yesterday, citing officials at the department.
The United States had deployed uncrewed drone speedboats for patrols as part of its operations against Iran, the Pentagon told Reuters, the first time the US had confirmed using such vessels in an active conflict.
Iran rejects 15-point plan
An Iranian official said that a 15-point US proposal, conveyed to Tehran by Pakistan, was reviewed in detail on Wednesday by senior Iranian officials and the representative of Iran's supreme leader, who felt it served only US and Israeli interests.
However, diplomacy had not ended, the official said.
The proposal included demands ranging from dismantling Iran's nuclear program to curbing its missiles and effectively handing over control of the strait, according to sources and reports.
Pakistan's foreign minister said "indirect talks" between the US and Iran were taking place through messages relayed by Islamabad, with other states including Turkey and Egypt also supporting mediation efforts.
Iran has hardened its stance since the war began, demanding guarantees against future military action, compensation for losses, and formal control of the strait, Iranian sources say.
It also told intermediaries that Lebanon must be included in any ceasefire deal, regional sources said.
Early this morning, Israel's military said it carried out "a wide-scale wave of strikes targeting infrastructure of the Iranian terror regime in the heart of Tehran".
In Lebanon, state media reported an airstrike on Beirut's southern suburbs, as AFP correspondents heard several explosions from the Hezbollah stronghold.
Iran launched multiple waves of missiles at Israel yesterday, striking Tel Aviv, Haifa and other areas, including a Palestinian town in central Israel.
At least one ballistic missile hit Tel Aviv, according to Israel's military, while others carried cluster missiles that dispersed smaller explosives, damaging homes and cars.
Israel's ambulance service said a man was killed in Nahariya after Hezbollah fired a rocket barrage at the northern city.
In Iran, strikes hit the southern city of Bandar Abbas and a village on the outskirts of the southern city of Shiraz. A university building in Isfahan was reported to have been hit.
At least six people were killed after a strike damaged three residential buildings in central Iran's Qom, the semi-official Fars news agency said, citing a provincial official.