Philippe Lazzarini, the leader of Unrwa, urged Israel to uphold law and order after claiming that armed gangs had looted two recent convoys close to the Kerem Shalom border.
Israel has previously claimed that it makes it easier for supplies to enter Gaza and charged Hamas with stealing and hijacking delivery.
The primary conduit for transporting aid to Gaza’s population of almost two million, which the UN has warned is in danger of starvation, is Kerem Shalom.
The distribution of goods has been hampered by a string of violent thefts by criminal gangs in recent weeks, according to charity workers.