Hamas's failure to secure the passages into the Gaza Strip drew criticism from an unlikely source on Thursday, John Ging, who heads the United Nation's Relief and Works Agency's operations in the Strip. "It is very clear the responsibility lies with the Palestinians," Ging told The Jerusalem Post by telephone from Gaza, on a day when Palestinians fired mortar shells at two of the three open passages into Gaza. Such activity, he said, "directly impacts on the humanitarian plight of the Palestinians living in Gaza." For security and technical reasons, following the Hamas takeover of Gaza, Israel has kept the main commercial thoroughfare into that territory, the Karni cargo crossing, mostly closed since June 12. It has been open on a limited basis for wheat since June 29. A relatively small amount of goods, mostly humanitarian aid, has instead entered Gaza through two secondary passages, at Sufa and at Kerem Shalom, both in the south. The Erez crossing in the north has been open for a small amount of pedestrian traffic and the transfer of medical supplies. The focus has been on Kerem Shalom and Sufa, because they are easier to secure than Karni, and even there the Palestinians have continued to fire mortar shells, said Shlomo Dror, the spokesman for the coordinator of government activities in the territories. On Thursday, 156 trucks with basic foods and animal feed passed through Sufa and Kerem Shalom, Dror said. It was an increase of some 50 trucks from the previous Thursday. More trucks could have gone through Kerem Shalom on Thursday if it hadn't been for the mortar attack, Dror said. Ging said he was grateful that goods were able to go through Kerem Shalom and Sufa. "But it is not a sustainable solution," he said. While the two passages have worked as a stopgap measure to ward off hunger, in the long run they would not suffice, he said. To prevent a deepening humanitarian and economic crisis, Hamas must secure the Karni crossing, Ging said. "The focus has to be on the Palestinian side, and the Palestinian officials have to meet the security requirements," he said. Sending food through Kerem Shalom and Sufa was much more time consuming, labor extensive and expensive than sending it through Karni, Ging said. And the two passages cannot accommodate the same volume of goods as Karni, he added. At Karni, there were a number of sophisticated mechanisms that allows goods to move directly from an Israeli truck to a Palestinian one, he said. At Sufa and Kerem Shalom, goods are unloaded from a truck and then reloaded, said Ging. "It is a huge effort and very expensive," he said. Gaza's food stores not being replenished as quickly as they are consumed, said Ging. He said he was particularly concerned that the lack of non-basic food supplies and the increase in poverty would make it impossible for Gazans to augment UN handouts with other forms of sustenance such as dairy products and fresh produce. The UN food packages only account for 61 percent of the total calories needed, he said. People "shouldn't be satisfied just to see the United Nations getting food into Gaza, it is not enough to sustain life on its own," he said. And the inability to bring commercial goods in or out of Gaza has crippled the economy, he said. Ging cited a report issued a day earlier by Gisha, the Legal Center for Freedom of Movement, which said that since the closure, 75% of Gaza's factories had shut down. The deepening poverty as a result of the closures meant that more humanitarian assistance would be needed, he said. "It is pushing more and more people into the poverty trap," Ging said. "You can not resuscitate an industry over night. This is our big concern, that there will be further economic collapse and further poverty, and the challenge of turning it around will be even greater," he said. If everything ground to a halt, one could open all the passages into Gaza and it still wouldn't help, he said.