More than half the population of Syria is likely to be in need of aid by the end of the year, the UN high commissioner for refugees has warned, while labelling the ever-worsening crisis as the most serious the global body has dealt with. António Guterres, who has led the UNHCR through the worst of the refugee crises in Afghanistan and Iraq, said the Syrian civil war was more brutal and destructive than both and was already the worst humanitarian disaster since the end of the cold war. His assessment came as the UN released new data on the numbers of refugees, which revealed that 6.8 million Syrians need aid. That figure is likely to reach at least 10 million, more than half the pre-war population of the country. Another UN body, Unicef, says half of those in need are children. "I don't remember any other crisis where we are having 8,000 per day [fleeing across borders], every day since February," Guterres said in an interview with the Guardian. "There will very likely be 3.5 million by the end of the year. We will have half the population of Syria in dire need of assistance and this is incomprehensible." With the civil war now into its third year and increasingly taking the shape of a proxy regional war fought across a sectarian faultline, aid groups are making ever more strident predictions of a catastrophic funding shortfall. Guterres goes further, warning that the modern boundaries of the Middle East and the post-Ottoman agreements that underpin them may unravel if the crisis is not brought to an end. "The political geography of the modern Middle East emerged from the Sykes-Picot agreement with the exception of the never-resolved Israeli-Palestinian situation," he said of the Anglo-French deal at the end of the first world war that eventually formed the nation states of Syria and Lebanon. "The conflict in Syria might for the first time put that political geography into question." The US secretary of state, John Kerry, and Syrian leader, Bashar al-Assad, this week both warned of a partition of the country that would inevitably cause grave ramifications in neighbouring Lebanon, Iraq and Jordan and beyond. Kerry appeared to advance the US position on Syria by suggesting an "enclave break-up" could only be prevented by getting "everybody on the same page with respect to what post-Assad Syria will look like". Assad, meanwhile, reiterated his earlier warning that no country in the region would be safe if the Syrian war, in which a majority Sunni opposition is fighting a minority Alawite regime aligned to Shia Islam, led to the collapse of the embattled state's borders. UNHCR figures show that close to 1.3 million Syrians have fled the country in the past two years. The figure is markedly lower than the numbers that have left Iraq and Afghanistan over the past decade, but is increasing at a faster rate than at any point in either country. In addition, there are thought to be at least 3 million internally displaced Syrian refugees, many of whom have limited means to provide for themselves or their families. Communities in Syria's war-ravaged north, west and south are largely without electricity and low on food and running water. Refugee camps in northern Jordan, southern Turkey and Lebanon's Bekaa valley are overwhelmed with daily arrivals of refugees who have often made precarious journeys to escape nearby battlefields. "This is the most brutal [conflict], even with very brutal conflicts elsewhere," said Guterres. "If one looks at the impact on the population, or the percentage of the total population in need, I have no doubt that since the end of the cold war it is the worst. And it will become even worse still if there is no solution. "My belief is that if we take all of these elements, then this is the most dramatic humanitarian crisis that we have ever faced. Then if we look at the geopolitical implications, I have no doubt that this is the most serious that we have ever dealt with." Lebanon and Iraq are increasingly unable to deal with the Syrian spillover, which is disturbing already fraught sectarian power bases and straining meagre resources during an economic downturn brought on by the crisis. "There is a real threat to Lebanon and Iraq," said Guterres. "Jordan is under serious economic stress. We have the Palestinian/Israeli question and the fact that the Syrian army has withdrawn from the Golan Heights. In the context of the Sunni-Shia divide, all the key actors are involved. Even compared to Afghanistan, the geopolitical implications and the threat to global stability are profound. It's the most dangerous of all crises." In an address to the United Nations security council on Thursday, Guterres said there had "not been an inch of progress towards a political solution". Expanding on that to the Guardian, he said: "It is of enormous frustration that we have come to such a situation in global governance that nobody can address it." Diplomacy on Syria has failed to bridge a yawning divide in views on what has fuelled the crisis and how best to deal with it. Russia and China, two permanent members of the security council, have blocked moves towards more robust support of the opposition in Syria. The US and Europe have attempted to impose ever tougher sanctions on the Assad regime, but have balked at arming the opposition because of concerns about the influence of al-Qaida groups. "I lived in a bipolar world," said Guterres. "Until the war in Iraq, I witnessed a unipolar world with one single superpower. Now we are in a clearly established multi-polar world. New actors have emerged – the Brics: China, Russia, Brazil, India. There is no longer a clear set of power relations. There is no way to bring about consensus among global players, or to bring about common action. There is no capacity to produce any solution." UN appeals for aid to Syria remain desperately under-funded with some agencies, including Unicef, reporting a shortfall of more than 70%. The crisis was eased somewhat on Thursday when Kuwait transferred $300m (£196m) to the UN for Syrian relief. "[It] will be distributed across all of our institutions," said Guterres. Kuwait is the only Gulf country that has honoured its promise through the multilateral aid organisations. "We can now put some money up front in Syria, but we are all in big trouble. Most of the western countries have huge budget difficulties. Moving towards 3 million refugees, there is no way that this can be dealt with. "The system is at breaking point. There is limited capacity to take many more. Where are the people going to flee? Into the sea?" Syrian refugees 1.35m: the number of refugees fleeing Syria who have sought protection in neighbouring countries, according to the UNHCR 48%: the percentage – at least – of the refugee population who are under 18. Some 77% are women and children $162.4m: the amount pledged by 4 April to Syria's Regional Response Plan by international donors – just 33% of UNHCR's requirements 10%: the increase in Lebanon's population due to refugee movements. Jordan's is up 6% Guardian
