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.
Seven dead, 82 missing in Indonesian landslide
Australian boy dies after shark attack in Sydney Harbour
One dead as Ukraine's two largest cities under Russian attack
US withdraws from World Health Organisation
To Lam wins second term to rule Vietnam for next five years
