Judges at the International Court of Justice have unanimously ordered Israel to take all the necessary and effective action to ensure basic food supplies arrive without delay to the Palestinian population in Gaza.
The ICJ said the population in Gaza face worsening conditions of life, and famine and starvation are spreading.
"The court observes that Palestinians in Gaza are no longer facing only a risk of famine (...) but that famine is setting in," the judges said in their order.
The new measures were requested by South Africa as part of its ongoing case that accuses Israel of state-led genocide in Gaza.
In January the ICJ, also known as the World Court, ordered Israel to refrain from any acts that could fall under the Genocide Convention and to ensure its troops commit no genocidal acts against Palestinians in Gaza.
In Thursday's order the court reaffirmed the January measures but added Israel must take action to ensure unhindered provision of basic services and humanitarian assistance including food, water and electricity as well as medical supplies and medical care to Palestinians throughout Gaza.
The judges added that this could be done "by increasing the capacity and number of land crossing points and maintaining them open for as long as necessary".
The court ordered Israel to submit a report in a month after the order to detail how it had given effect to the ruling.
Meanwhile, Palestinian Prime Minister Mohammad Mustafa formed a new cabinet on Thursday in which he will also serve as foreign minister, making an immediate ceasefire and Israeli withdrawal from Gaza a priority, Palestinian news agency WAFA reports.
Mustafa, an ally to President Mahmoud Abbas and a leading business figure, was appointed prime minister this month with a mandate to help reform the Palestinian Authority (PA), which exercises limited self-rule in the Israeli-occupied West Bank.
He was also assigned to lead the relief and rebuilding of Gaza, which has been shattered by more than five months of war, while he performs double-duty as foreign minister replacing Riyad al-Maliki who had served in the position since 2009.
Abbas, who as president remains by far the most powerful figure in the PA, appointed the new government in a demonstration of willingness to meet international demands for change in the administration.
He approved Mustafa's cabinet with financial expert Omar al- Bitar as finance minister, and Muhamad al Amour - who served as the president of the Palestinian Businessmen Association - as economy minister.
He kept Ziad Hab al-Reeh, former chief of the PA's internal intelligence agency, as interior minister, WAFA said.
The new cabinet, which includes eight ministers from Gaza, will also include a state minister for "relief affairs".
Mustafa said in a statement addressed to Abbas that the first priority was an immediate ceasefire in Gaza and a complete Israeli withdrawal from the enclave, in addition to allowing humanitarian aid to enter in large quantities and reaching all areas, WAFA reported.
"In order to enable the launch of the recovery process and preparation for reconstruction, stop the aggression and settlement activities, and curb settlers' terrorism in the West Bank," Mustafa added.
Hamas, the Islamist movement that controlled Gaza until Israel's invasion following the October 7 attack on southern Israel, has criticised the appointment of Mustafa but it had no immediate reaction to the naming of his new cabinet.
The PA, controlled by Abbas' Fatah political faction, has long had a strained relationship with Hamas and the two factions fought a brief war before Fatah was expelled from the territory in 2007.
However it has repeatedly condemned the Israeli invasion of the Gaza Strip and has insisted it must play a role in running Gaza after the war, a position supported by the United States.
