The United Nations refugee agency in Gaza Strip has not built any schools in the past three years because the Israeli blockade prevented the importation of construction materials, dpa quoted a UN official as saying today. As a consequence, tens of thousands of Palestinian children have had no opportunity to attend school, said John Ging, the director of the UN refugee work agency operation in the territory. He said there are about 50,000 new born Palestinians a year in the Gaza's 1.5- million population. The Israeli blockade of Gaza, which began in 2006, tightened during and after the Hamas-Israel conflict in the winter of 2009. In response to repeated UN demands, Israel relaxed the blockade last year with some crossings into Gaza opened for trucks carrying mostly humanitarian and medical supplies. UN Secretary General Ban Ki-moon has called the limited number of trucks entering Gaza a "drop in a bucket." Ging said the description was correct because of the constant huge scale of needs by the Palestinian population, whose living conditions remained dire. "We have not been able to build any schools in the past three years," Ging said at a news conference at UN headquarters in New York. "We need to move beyond a drop of this and a drop of that." Ging said makeshift school classrooms had been built with all kinds of materials for some of the children, but those temporary means have been exhausted. He said "thousands" of children have not had regular education because of the lack of schools. Ging said the Palestinians have smuggled construction materials through tunnels dug under boundaries with Egypt, which were used by the government in Gaza. But Ging said the UN cannot use those materials because they were illegally imported. He described the humanitarian conditions in Gaza as desperate more than a year after the Hamas-Israeli fighting, with the Gazans having no legitimate economy and trade on which to survive.