"Israel's strike on negotiators in Doha on September 9 was a shocking breach of international law," Volker Turk told the UN Human Rights Council.

Israel targeted Hamas leaders last week in strikes on the Qatari capital, killing five Hamas members and a Qatari security officer.

The attack drew widespread international condemnation, including from Gulf monarchies allied with the United States, Israel's main backer.

Opening an urgent debate on the strike before the council, Turk described it as "an assault on regional peace and stability, and a blow against the integrity of mediation and negotiating processes around the world".

"As such, I condemn it and call on this Council and all governments to do the same."

The council announced on Monday that it would convene the 10th urgent debate since its creation in 2006 following two official requests from member states of the Organization of Islamic Cooperation of the Cooperation Council for the Arab States of the Gulf.

Israel, which disengaged from the rights council earlier this year, reacted angrily to the news of the urgent debate.

"This marks yet another shameful chapter in the Human Rights Council's ongoing abuse," Israel's ambassador to the UN in Geneva, Daniel Meron, told journalists.

He accused the council of "serving as a platform for anti-Israel propaganda, while ignoring the brutal realities on the ground and the atrocities committed by Hamas".

Turk said Israel's September 9 attack "violated the right to life under international human rights law and the principles of international humanitarian law".

"Targeting parties engaged in internationally supported mediation on its territory undermines Qatar's key role as a facilitator and peace broker.

"It is an attack on global efforts to resolve conflicts peacefully," he said.

The UN High Commissioner for Human Rights called on the council "to reaffirm the central importance of mediation processes and to call for accountability for unlawful killings".