Southern Gaza is turning into a “pressure cooker”, where the majority of people – faced with dwindling food, inadequate water sanitation, overcrowding and a crumbling hospital service – want to flee, the deputy director of the UN agency for Palestinians has said. Scott Anderson of the United Nations Relief and Works Agency (UNRWA), who is engaged in daily negotiations to gain Israeli permissions for aid convoys to enter and move around Gaza, said it was in “a full-time emergency” and just six of the 21 planned convoys to the north of the territory had been granted access since January despite a UN security council resolution in December calling for relief to be stepped up. “The truth is I have not seen any change in the reality on the ground since the passing of that UN resolution. There has been no reduction in either the number of Israeli or Egyptian inspection checks since the resolution was passed,” he told the Guardian. “Sometimes it feels like the story of the little boy in the dyke – trying to plug a million holes is how it feels. Each day I feel like it’s very much a two steps forward, two steps back. It’s pretty much a full-time emergency.” Anderson, who first worked for UNWRA in 2008 after 21 years in the US army, has his office in Rafah in the southern part of the Gaza Strip, where from the roof he can look across at a sea of makeshift tents. “There were 280,000 people here. Now there’s 1.4 million. It’s very difficult for any community to absorb that many people in that short amount of time. And let’s say this graciously, the sewage networks in Gaza weren’t the most robust before the conflict.” He added: “Certainly we do worry about the pressure cooker, and I think if there was an opportunity, most people would flee to Egypt.” The mass displacement of Palestinians, he said, was having a deep impact on societal bonds. “It’s very family based society, or almost tribal based. Those family dynamics have been interrupted, because now people are around people that they were never near before. It’s impacted how society functions and some of the constraints have come off. “We have to make sure we take care of people in Rafah and respond to their needs. If we lose our presence here, we lose access to the rest of Gaza and we can’t get anywhere. The crossings into Gaza are currently in the south. It’s extremely challenging to feed a million and a half people only through humanitarian assistance and with very little commercial sector activity.” Anderson, who said he talked daily with Cogat, the Israeli military’s civil agency for the Palestinian territories and its coordination and liaison administration (CLA), said he would like to see crossings open seven days a week instead of the current five, direct access to northern Gaza and more open discussion with Israeli officials, whom he described as very professional, on access for aid convoys. “We’re not rigid in our requirements,” he said. “We are happy enough if they say: ‘You can’t go to Deir al-Balah today, but you can go to Gaza City,’ to adjust our approach and go to Gaza City. But that requires a conversation about what is possible, rather than just what is not. “So the way it works is like the day before, like for tomorrow, we’re going to request a mission for the World Health Organization or for Unicef to go do refuelling for water wells. So we do Google coordinates of where the wells are. We give vehicle details in terms of plate numbers, drivers, all these kinds of things. That gets submitted to them. And they work through their process, and usually, we have an answer, yes or no, often quite late.” The CLA’s chief, Col Moshe Tetro said at a briefing on Wednesday: “There is no food shortage in Gaza. In terms of food, the reserves in Gaza are sufficient for the near term.” One of his running conversations with Israel is for convoys to be able to access northern Gaza, where Israel says it has now dismantled Hamas. “There are 300,000 people living in the north, but I don’t think anybody knows for sure. Other than during the ceasefire there hasn’t been anything really of scale, going to people in the north. So we’re fairly certain they’re very hungry, if not approaching starvation levels. More broadly he said: “What we’re asking for in general is 600 trucks of aid a day into Gaza, and right now we are around 150 on average. We want 300 a day for the private sector, 200 a day for the UN and 100 a day for the Palestinian Relief Committee. He said he would love it if the crossings remained operational by night but accepted the security environment and the need for police protection made it difficult for convoys to travel outside daylight. But he said he was firmly committed to the UN being able to reach 200 a day so long as the obstacles could be removed in Egypt and Israel. He explained that if a truck came from Arish in Egypt it was first screened at the Rafah crossing, where Egypt has its own screening facility. From there it goes about 60km (about 37 miles) to the smaller Israeli Nitzana crossing for screening, and then returns to Rafah – or from Rafah to the recently re-opened Kerem Shalom crossing for screening by the Israelis. “Everything gets screened twice,” he said. He absolutely rejects the charge that the UN trucks over the years have been a witting or unwitting conduit to arm Hamas. “We have a very strict and diligent process that we go through to make sure aid gets to the people that it should get to. I worked in Gaza from 2008 to 2015, and I’ve come back for this conflict specifically. All the stuff that Hamas is using did not come overland. It came in underground through the tunnels.”