UN Secretary-General Antonio Guterres has used a rarely exercised power to warn the Security Council of an impending “humanitarian catastrophe” in Gaza and urged its members to demand an immediate humanitarian ceasefire.

His letter to the council’s 15 members on Wednesday said Gaza’s humanitarian system was at risk of collapse after two months of war that has created “appalling human suffering, physical destruction and collective trauma”, and he demanded civilians be spared greater harm.

Guterres invoked Article 99 of the UN Charter, which says the secretary-general may inform the council of matters he believes threaten international peace and security. “The international community has a responsibility to use all its influence to prevent further escalation and end this crisis,” he said. UN spokesman Stephane Dujarric said he expects the secretary-general to address the Security Council on Gaza this week.

A short draft resolution circulated to council members late on Wednesday by the UAE, the Arab representative on the council, would act on Guterres’ letter under Article 99. It demands “an immediate humanitarian ceasefire” and expresses “grave concern over the catastrophic situation.