In the heavily blockaded Gaza Strip, cigarettes have become a rare commodity, often selling for $25-30 each. Both U.N. and Israeli officials have reported that coordinated attacks by groups seeking to profit from these contraband cigarettes are severely hampering the transportation of essential aid into southern Gaza.

Israeli authorities carefully monitor all goods entering and leaving Gaza through checkpoints under their control. Despite these efforts, cigarettes have managed to pass for weeks inside aid trucks, mainly through the Kerem Shalom crossing in southern Gaza.

To evade Israeli controls, traffickers in Egypt hide cigarettes in sacks of flour, diapers and even watermelons donated by the United Nations, according to aid agencies and an Israeli military official who provided photos to The New York Times.

Humanitarian aid trucks leaving the Gaza border crossing have been attacked by armed Palestinians searching for hidden cigarettes, according to Israeli and United Nations officials.

Andrea De Domenico, head of the UN Office for the Coordination of Humanitarian Affairs in Jerusalem, confirmed that aid officials had discovered “UN-branded aid boxes with cigarettes inside.” He noted that the smuggled cigarettes had created a “new dynamic” of organized attacks on aid convoys.

Israel’s tight control over goods entering Gaza during the conflict has significantly distorted the enclave’s economy. While the price of flour has fallen in some areas due to large quantities being admitted under international pressure, other goods remain scarce and expensive.

Mr. De Domenico shared with The Times footage of a recent drive along the road from Kerem Shalom to Gaza, showing sacks of flour left on the side of the road, apparently of little interest to looters.

“Their main goal here was to find cigarettes,” said Manhal Shaibar, who runs a Palestinian trucking company in Kerem Shalom that transports United Nations aid.

Officials said most of the cigarette trucks appeared to be coming from Egypt. These trucks were diverted through Kerem Shalom after Israel took control of the Rafah border crossing in early May. Mr. Shaibar attributed the smuggling operations to Bedouin families in both Gaza and Egypt’s Sinai.

The looting is a consequence of the chaos that has engulfed much of Gaza as Israel’s war against Hamas enters its 10th month. Israeli forces have dismantled Hamas’s government and police structures without establishing a new administration, resulting in widespread lawlessness.