By contrast, U.N. data shows that a total of 533 aid trucks entered Gaza in the three days after Saturday. More broadly, U.N. figures show no increase in the daily average of trucks going into Gaza in the first week of April, compared to the previous week.

The reasons for the discrepancy are not clear, but one is the differing methods Israel and the United Nations use to track trucks, said Jens Laerke, a spokesman for the U.N. humanitarian office.

Trucks screened — and counted — by Israel at the two working border crossings usually enter Gaza only half full, after Israeli inspectors prohibit some of their contents, said Mr. Laerke. Once inside Gaza, they are unloaded, repacked as full trucks and sent to warehouses operated by the United Nations, which counts the number of full trucks that arrive, likely leading to a lower tally.

Other complications also mean that trucks often don’t pass through a crossing and arrive at a warehouse in the same day, meaning the daily counts at crossings and the warehouses often do not match, he said.

In a statement on Wednesday, COGAT criticized the U.N.’s “flawed counting method,” which it called “an attempt to conceal their logistical distribution difficulties.”

Previous Israeli promises to scale up aid have not greatly increased deliveries. Under U.S. pressure in mid-December, Israel reopened one crossing to Gaza, Kerem Shalom, for aid trucks, committing to permit 200 trucks a day to enter. But aid agencies say that stringent Israeli inspections have kept the numbers far lower than what is needed.

And Mr. Laerke and other aid officials said enormous challenges remain to distributing the aid inside Gaza, particularly to the north, where Israel has denied access for UNRWA, the main U.N. relief agency working in the territory.