A resumed Israeli military assault in the overcrowded south of Gaza may lead many of 1 million refugees – including 900,000 sheltering in UN buildings – to try to push over the border into Egypt, the head of the UN’s Palestine relief agency UNRWA has warned. After a second overnight visit to Gaza where he met overwhelmed Palestinians, Philippe Lazzarini urged Israel to think through the consequences of an offensive in the south if the temporary truce in the fighting is not extended. “We already have a staggering human tragedy,” he said in an interview, adding the prospect of a further assault feels him with deep anxiety and foreboding. “We are in a race against time, and already disease is becoming as much a threat as the bombardment […] The combined impact of the bombardment and the siege has already pushed people to the south, if there is fighting there is indeed a higher likelihood that they might wish to flee further south and beyond the border.” Lazzarini has become one of the most outspoken UN humanitarian officials in recent weeks, urging Israel to abide by the rules of law and proportionality. He is concerned about the impact of fighting in the south, which he described as “completely overloaded” after Israel urged civilians in the north of the territory to move south for their own safety. “The Gaza Strip was already known as being one of the most crowded places in the world. And now, you have the majority of the population moved towards the south,” he said. “So, you have the almost complete concentration of the population in half the territory – an area that cannot support such a presence because of even the lack of water. “It simply cannot cater to so many people. Remember people from Gaza City and the north have been asked to go to the south because they were told the south would be safer. Yet a large proportion have been killed in the south.” Equally, Lazzarini says the concept of unilateral safe zones in the south for civilians, if they are not agreed with Hamas, is full of risk. “We have 1 million people, 1 million people in UN installations, including 100,000 in the north. They come to seek protection. “Their locations are known, and despite that, nearly 100 installations have been hit directly or indirectly. And this has led to the deaths, the killing of more than 200 people, and the injuries are more than 900 in UN installations. “Now, we are told, or we hear, that people should move further south-west if the offensive takes place in Khan Yunis […] but you cannot declare an area safe unilaterally in a war zone.” Asked whether his call for an extended ceasefire would leave Hamas entrenched and Israel’s security compromised, as Israel suggests would be a consequence, he answered in terms of Gaza’s civilian population: “Gaza is not Hamas. You have an organisation called Hamas and you have a population and this population is diverse, vibrant, cannot be equated to Hamas. “It’s a population, which has lived under the rule of Hamas over the last 17 years. Does it mean that the entire population – half of it are children, half of it were born after Hamas came to power – have to pay the price? “It’s an equation which has to be addressed by those who made the objective to neutralise or eliminate Hamas. What we are saying is that the objective cannot be at the expense of this civilian population. That is the reason why you have a rule of war. The reason why you have an international humanitarian law.” He also urged Israel to think of its world standing. “The longer this war lasts, and the more people die there will be a very strong feeling in the region that international humanitarian law does not apply the same for everyone, the further the region will be polarised, and the further we will be from any peace prospect in the future,” he said. “We should never ever underestimate this feeling not just in Gaza, but in the region”. Lazzarini has no compunction going beyond saying Israel should abide by the rules of war to asserting that it is not doing so – a step the US and British administrations decline to take – and he believes it will be up to an international legal body to determine the facts in future. “My only observation here is that imposing a siege on an entire population seems to me to be a collective punishment,” he says. “The most difficult concept in international humanitarian law is the concept of proportionality, but we have to be careful not to use this notion to justify the unjustifiable. “Personally I don’t see how we can justify through the concept of proportionality and distinction, the killing of more than 15,000 people in 40 days, and among them, so many women and children. I don’t see how this can be justified through the concept of proportionality and self-defence. That’s a very personal view. By any account these are staggering figures, and a staggering human tragedy.” Admitting the humanitarian agencies are in a race against time before the temporary truce is likely to end, he pleaded for more than 200 trucks a day to be allowed to cross the Rafah crossing and for more crossings to be opened by Israel. He clearly feels haunted by his visit to an UNRWA training centre last week. “We are hosting 35,000 displaced people there and people are living in just appalling unsanitary living conditions. You have sewage water starting to pour into the courtyard of the compound. The doors of the compound were locked just like a closed prison because it cannot host more people. It was shocking. “People arrived 30-40 days ago, and had left everything behind. Most of them have seen their houses and apartments destroyed, and are still living in the clothes in which they arrived 40 days ago. “I talked to a father who suddenly burst into tears when he started to describe the living conditions and how he feels. His family are living in the four square metres of space, sleeping on the concrete floor. They have no mattress, they have no blanket, they are struggling to have one meal a day which is primarily canned food or, or piece of bread. They are queueing to get water. They’re queueing for hours to go to the toilets. “He said to me: ‘Well, I feel humiliated. I feel stripped, we feel stripped of our dignity, we feel lost, we feel useless, we feel broken.’ And his story is a story of almost anyone living there.”