U.N. chief António Guterres invoked a rarely exercised clause in the U.N. Charter to push for an Israel-Hamas cease-fire, warning the organization’s security council that urgent action is necessary to help Gaza avert a “humanitarian catastrophe.”

In a dramatic move, Guterres on Wednesday wrote to members of the Security Council and urged them to collectively call for a full humanitarian cease-fire.

He said that two months of war had “created appalling human suffering, physical destruction and collective trauma across Israel and the Occupied Palestinian Territory.”

“The international community has a responsibility to use all its influence to prevent further escalation and end this crisis. I urge the members of the Security Council to press to avert a humanitarian catastrophe,” Guterres said.

“This is urgent. The civilian population must be spared from greater harm. With a humanitarian ceasefire, the means of survival can be restored, and humanitarian assistance can be delivered in a safe and timely manner across the Gaza Strip.”

It is the first time that Guterres has invoked Article 99 of the U.N. Charter, which states that the U.N. chief “may bring to the attention of the Security Council any matter which in his opinion may threaten the maintenance of international peace and security.”

The move renewed personal tensions between Guterres and Israeli officials. Israeli Foreign Minister Eli Cohen on Wednesday said the U.N. chief’s tenure was “a danger to world peace” and suggested his push to activate Article 99 constituted support of the Palestinian militant group Hamas.

A U.N. spokesperson was not immediately available to comment when contacted by CNBC on Thursday. It has previously dismissed claims that it is biased over the Israel-Hamas war.

Late last month, Israel’s representative to the U.N. called for Guterres to resign, saying he had “lost all morality and impartiality.”

The call came after the U.N. chief said it was important to recognize the Oct. 7 attacks by Hamas “did not happen in a vacuum,” citing “56 years of suffocating occupation” suffered by the Palestinian people.

U.N. Spokesperson Stéphane Dujarric described Article 99 as “the most powerful tool” at the U.N. chief’s disposal, saying that Guterres had invoked the article “given the scale of the loss of human life in Gaza and Israel, in such a short amount of time.”

Dujarric added that Guterres hoped the move would ratchet up the pressure on both the council’s 15 members and the international community at large to demand a cease-fire.

The Security Council, which consists of five permanent members with veto power and 10 non-permanent members, has not yet adopted a resolution calling for a cease-fire between Israel and Hamas.

China, France, Russia, the U.K. and the U.S. all hold veto power on the council, which is regarded as the U.N.’s most powerful body.

The U.S. used that veto power on an Oct. 18 resolution that called for “humanitarian pauses” in the fighting to deliver aid to Gaza.

In mid-November, the council passed a resolution to call for “urgent and extended humanitarian pauses.”

The International Energy Agency on Thursday said that oil markets are likely to remain on edge as the Israel-Hamas war persists, with investors closely monitoring the potential for output disruption in the Middle East.

The world’s leading energy watchdog said in its latest monthly oil market report, that while the conflict had not yet had a direct impact on physical supply, energy market participants would “remain on tenterhooks” as the crisis unfolds.

“The Middle East conflict is fraught with uncertainty and events are fast developing,” the IEA said in its report.

“Against a backdrop of tightly balanced oil markets anticipated by the IEA for some time, the international community will remain laser focused on risks to the region’s oil flows,” the energy agency added.

Noting a “sharp escalation in geopolitical risk,” the IEA said it would continue to closely monitor oil markets and “stands ready to act if necessary to ensure markets remain adequately supplied.”

In the event of an abrupt oil supply shortage, the IEA’s response includes member countries releasing emergency stocks and/or implementing demand restraint measures.

Israel is not a major oil producer and no major oil infrastructure runs close to the Gaza Strip.

The IEA notes, however, that the Middle East accounts for more than one third of global seaborne oil trade, and the Israel-Hamas conflict has ratcheted up fears the fighting may affect regional energy production.

The IEA report comes as the Israel-Hamas conflict enters its sixth day and follows a devastating and coordinated assault from Palestinian militant group Hamas on southern Israel over the weekend. Israel has since pulverized Gaza with airstrikes and is expected to launch a ground offensive against Hamas in the region in the coming days.

Israel has also ordered the “complete siege” of the Gaza Strip, seeking to stop the supply of electricity, food, water and fuel to the already blockaded population of roughly 2.3 million people.

As a result of the ongoing Israeli-Hamas war, at least 1,200 Israelis have been killed, with more than 2,700 injured, according to Israel’s military. Meanwhile, the Palestinian Ministry of Health says 1,203 people in Gaza have been killed, with 5,763 injured.

When oil markets opened following the surprise attack by Hamas on Israel on Oct. 7, the IEA said traders priced in a $3 to $4 risk premium. However, prices have since stabilized.

Crude futures traded higher on Thursday.

International benchmark Brent crude futures with December expiry traded 0.8% higher at $86.5 per barrel at around 9 a.m. London time, while front-month November U.S. West Texas Intermediate crude futures rose 0.6% to trade at $83.99 per barrel.