UNITED NATIONS  John Ging, the director of operations for the United Nations refugee agency in Gaza, said Thursday that Israel’s blockade was creating growing misery there by choking off basic humanitarian supplies like food, medicine, clothes and blankets as well as school supplies.

He also criticized the leadership of Hamas for letting its police force run wild, attacking a distribution center for the needy to cart off supplies.

“We are neither getting in the volume nor the range of supplies that we need here,” Mr. Ging told reporters at the United Nations, speaking via video link-up from Gaza. “This is creating a lot of misery among the people.”

In one example, Mr. Ging said that the teachers in the schools run by the United Nations Relief and Works Agency had worked throughout the three-week Israeli bombardment that ended Jan. 18 to create a new human rights curriculum. But because Israel was blocking paper supplies, the textbooks and workbooks could not be printed, so some 60 percent of the children in United Nations schools lack books.