GENEVA－The January US drone strike in Iraq that killed senior Iranian general Qasem Soleimani and nine other people represented a violation of international law, a United Nations human rights investigator has said.

The United States has failed to provide sufficient evidence of an ongoing or imminent attack against its interests to justify the strike on Soleimani's convoy as it left Baghdad airport, said Agnes Callamard, UN special rapporteur on extrajudicial, summary or arbitrary executions, on Monday.

The attack violated the UN Charter, Callamard wrote in a report calling for accountability for targeted killings by armed drones and for greater regulation of the weapons.

"The world is at a critical time, and possible tipping point, when it comes to the use of drones. ... The Security Council is missing in action; the international community, willingly or not, stands largely silent," Callamard said.

Callamard is due on Thursday to present her findings to the UN Human Rights Council, giving member states a chance to debate what action to pursue. The US is not a member of the forum, having quit two years ago.

Pivotal figure

Soleimani, leader of the Iranian Revolutionary Guard's elite Quds Force, was a pivotal figure in orchestrating Iran's campaign to drive US forces out of Iraq and the Middle East. Washington had accused Soleimani of masterminding attacks by Teheran-backed militias on US forces in the region.

"Major General Soleimani was in charge of Iran military strategy, and actions, in Syria and Iraq. But absent an actual imminent threat to life, the course of action taken by the US was unlawful," Callamard wrote in the report.

The Jan 3 drone strike was the first known incident in which a nation invoked self-defense as a justification for an attack against a state actor in the territory of a third country, Callamard added.

Iran retaliated with a rocket attack on an Iraqi air base where US forces were stationed. Hours later, Iranian forces on high alert mistakenly shot down a Ukrainian passenger airliner taking off from Teheran.

Iran has issued an arrest warrant for US President Donald Trump and 35 others over Soleimani's killing and has asked Interpol for help, Ali Alqasimehr, a prosecutor of Teheran, said on June 29, according to the semi-official Fars news agency.

Alqasimehr said he would continue to pursue his prosecution even after Trump's presidency ends.

Agencies via Xinhua