South African President Cyril Ramaphosa accused Israel of war crimes and "genocide" in Gaza, as he chaired an extraordinary summit of the BRICS group of nations on Tuesday.
Pretoria is hosting a virtual meeting of BRICS -- a group of major emerging economies that includes Brazil, Russia, India, China and South Africa -- aimed at drawing up a common response to the Israel-Hamas conflict.
"The collective punishment of Palestinian civilians through the unlawful use of force by Israel is a war crime. The deliberate denial of medicine, fuel, food and water to the residents of Gaza is tantamount to genocide," Ramaphosa said.
Fighting has raged in Gaza after Hamas gunmen killed around 1,200 people, mostly civilians, during cross-border raids on October 7 -- the deadliest attack in Israel's history.
In retaliation, Israel launched a relentless bombing campaign and ground offensive in Gaza, which is ruled by Hamas.
According to Hamas, the war has killed more than 13,300 people, thousands of them children.
On Tuesday, Hamas leader Ismail Haniyeh said a truce agreement with Israel was in sight, with mediator Qatar adding negotiations to free hostages seized by the Palestinian Islamist group were at their "closest point" to a deal.
Ramaphosa called for an "immediate and comprehensive ceasefire" and the deployment of a UN force "to monitor the cessation of hostilities and protect civilians."
"As individual countries, we have demonstrated our grave concern at the death and destruction in Gaza," he told the summit.
"Let this meeting stand as a clarion call for us to combine our efforts and strengthen our actions to end this historical injustice."
South Africa has long been a vocal supporter of the Palestinian cause, with the ruling African National Congress (ANC) party often linking it to its own struggle against apartheid.
Earlier this month, Pretoria recalled all its diplomats from Israel and last week it joined four other nations in calling for an International Criminal Court investigation into the conflict.
On Monday Israel's foreign ministry said it had also recalled its ambassador to Pretoria for consultations.