GENEVA — A Belgian-drafted resolution that would establish an independent investigative mechanism into civilian harm during the seven-week Iran conflict opened a UN Human Rights Council special session here on Sunday, drawing immediate opposition from Iran and Israel and exposing the limits of the post-ceasefire diplomatic consensus that mediators have spent the past month trying to consolidate.

The draft, circulated to council members late Friday and obtained by reporters Saturday evening, would authorize a three-person panel of independent experts to collect and preserve evidence of violations of international humanitarian law committed between March 1 and April 15, with a mandate covering strikes on hospitals, water and electrical infrastructure, and civilian shipping in the Persian Gulf and Gulf of Aden. The mechanism would not have prosecutorial authority but would assemble files for transmission to “competent national or international jurisdictions” — a phrasing that diplomats said had been deliberately left ambiguous to keep both European and Latin American supporters on board.

Belgian Foreign Minister Maxime Prévot, who flew to Geneva on Saturday to introduce the text personally, told reporters at the Palais des Nations that the resolution was “not about choosing a side, it is about choosing a standard.” Prévot said co-sponsorship had grown to 27 states by Sunday morning, with the addition of Chile, Mexico, South Korea and Norway over the weekend, and that informal canvassing suggested a working majority among the council’s 47 members.

“What happened between March and April was a regional war fought with twenty-first-century weapons and twentieth-century rules,” Prévot said. “If the council cannot find its voice on civilian protection now, it will struggle to find it on anything else.”

The session, formally requested by Belgium, Costa Rica and Slovenia under the council’s emergency procedures, is scheduled to run through Tuesday, with a vote on the resolution expected late Tuesday afternoon. Council President Ambassador Federico Villegas of Argentina opened proceedings shortly after 10 a.m. with a brief reminder that the body’s mandate was “neither to litigate nor to legislate, but to illuminate.”

Iran’s permanent representative in Geneva, Ali Bahreini, rejected the draft in opening remarks delivered in Farsi and English, calling it “a selective exercise in moral accounting” and accusing European sponsors of ignoring what he termed “the strategic origins of the war in Tel Aviv and Washington.” Bahreini said Tehran would not cooperate with any mechanism established under the resolution and warned that adoption could complicate Iran’s compliance calendar under the Doha framework agreed on May 4.

Israel, which holds observer status at the council, broke pattern by dispatching a senior legal adviser from the Foreign Ministry, Tamar Goldfarb, who said the resolution “ignores the documented record of Iranian attacks on civilian targets in Tel Aviv, Eilat and Haifa” and called the proposed mandate “unbalanced on its face.” A Foreign Ministry statement from Jerusalem said Israel would not participate in the mechanism and would press friendly states to seek narrowing amendments.

The United States delegation, led by Acting Permanent Representative Christopher Lu, has taken a more cautious public posture. Lu said Washington shared “the deep humanitarian concerns” motivating the resolution but believed the council’s intervention was “premature” while the Doha verification calendar remained in its early stages. Two U.S. officials, speaking on condition of anonymity, said the administration was considering an abstention rather than a no vote, and was encouraging European co-sponsors to accept a six-month implementation pause that would defer the mechanism’s launch until after the August milestone in the IAEA monitoring schedule.

“The administration’s instinct is to protect the Doha track from anything that could give Tehran a pretext to walk away,” said Rafael Mendes, a former U.S. diplomat now at the Center for Strategic and International Studies. “But abstaining on a civilian-harm resolution carries its own political cost, particularly with the House Foreign Affairs hearings scheduled for next week. The calculation is genuinely difficult.”

European positions have largely consolidated behind the draft. France and Germany are co-sponsors; Italy is leaning supportive but has sought clarifying language on the scope of evidence collection in Yemen, where Riyadh has objected to any reference to Saudi-led coalition strikes. The United Kingdom is expected to vote in favor but will press for explicit references to Iranian missile strikes on civilian sites. EU foreign policy chief Marta Stenberg, attending Sunday, said the bloc viewed accountability and reconstruction as “two tracks that must run in parallel, not in sequence.”

Among non-aligned members, the picture is more fluid. South Africa’s representative, Mxolisi Nkosi, said Pretoria supported the principle of investigation but wanted the mandate widened to cover the period preceding March 1. Pakistan, which co-chairs the Doha framework, has not declared a position; Foreign Minister Ishaq Dar, asked Saturday in Islamabad whether the resolution might complicate his mediation, said only that “every forum has its work, and ours is to keep the calendar moving.” Russia and China, both of which abstained on the Security Council resolution endorsing the Islamabad framework on April 26, signaled Sunday they would vote against the draft, with Russian Ambassador Gennady Gatilov calling the mechanism “a politicized instrument designed to substitute for diplomacy.”

Civil society participation has been heavy. Representatives of Amnesty International, Human Rights Watch and the Iranian-American advocacy group NIAC each addressed the session, and a coalition of Yemeni and Iraqi NGOs urged the council to ensure that any investigation cover damage to water infrastructure in Basra and Hodeidah. Layla Hassan, a Beirut-based regional analyst at the Levant Policy Forum, said the mechanism’s value would depend less on the resolution’s text than on its staffing. “Three experts and a small secretariat can do very little or very much,” she said. “We have learned that from Syria and from Myanmar.”

Mediators from the Doha framework, who had hoped that this week’s diplomatic focus would shift to preparations for the May 26 Muscat round on missile and drone restraint, watched the Geneva proceedings warily. Qatari Foreign Minister Mohammed bin Abdulrahman Al Thani, asked in Doha on Saturday whether the resolution risked destabilizing the framework, said the chairs took “no position on the work of other bodies” but hoped that “every capital will remember which conversations are about the past and which are about the next ninety days.”

Officials said the council would adjourn Sunday evening to allow further consultations, with formal debate resuming Monday morning and a final vote tentatively set for Tuesday at 5 p.m. local time. A second resolution, on humanitarian access to conflict-affected areas, is expected to be tabled later in the week.