Around one million people have fled the Gazan city of Rafah in the past three weeks, the United Nations Palestinian refugee agency (UNRWA) said on Tuesday.
The small city on the southern edge of the Gaza Strip had been sheltering more than a million Palestinians who fled Israeli assaults on other parts of the enclave.
Since early May, Israel's military has been carrying out what it says is a limited operation in Rafah to kill fighters and dismantle infrastructure used by Hamas. It has told civilians to go to an "expanded humanitarian zone" some 20 kilometres away.
Many Palestinians have complained they are vulnerable to Israeli attacks wherever they go and have been moving up and down the Gaza Strip in the past few months.
UNRWA said the flight from Rafah "happened with nowhere safe to go and amidst bombardments, lack of food and water, piles of waste and unsuitable living conditions."
Providing assistance and protection is becoming nearly "impossible", the agency said.
Qatar's prime minister said on Sunday that efforts to reach a new ceasefire in Gaza have made some progress but an agreement between Israel and Hamas to end the war remains elusive.
A huge blast most likely caused by the explosion of chemical materials killed at least 18 people and injured more than 700 on Saturday at Iran's biggest port, Bandar Abbas, Iranian state media reported.
The UN Refugee Agency (UNHCR) and the UN Office for the Coordination of Humanitarian Affairs (OCHA) have sounded the alarm over severe funding shortfalls that are hindering life-saving humanitarian aid in countries including Nigeria, Burundi, and Colombia.
A number of people were killed and multiple others were injured in Vancouver after a vehicle drove into a crowd at a Filipino street festival in the western Canadian city, police said on Saturday.