More than one million Syrians have registered as refugees in Lebanon after fleeing war in their country, inflicting a "staggering" impact on the tiny Mediterranean country, the UN said on Thursday.
Refugees from Syria, half of them children, now equal a quarter of Lebanon's resident population, the UN refugee agency said in a statement, warning that most of them live in poverty and depend on aid for survival.
The UNHCR branded the one million figure as "a devastating milestone worsened by rapidly depleting resources and a host community stretched to breaking point".
Tiny Lebanon has now become the country with "the highest per capita concentration of refugees worldwide," and is "struggling to keep pace", it said in a statement.
The massive refugee crisis is compounded by a spillover across the border of the violence that has ravaged Syria for the past three years, with Lebanon experiencing frequent bombings and clashes even as it grapples with political deadlock and an economic downturn.
UNHCR chief Antonio Guterres urged increased international action, warning that the impact of the refugee crisis on Lebanon is "staggering" and "immense".
"Lebanon hosts the highest concentration of refugees in recent history. We cannot let it shoulder this burden alone," Guterres said in the statement.
"Lebanon has experienced serious economic shocks due to the conflict in Syria", while security has deteriorated as a result of rising regional instability, he added.
Lebanon's social affairs minister Rachid Derbas too appealed for greater international support for his country as it struggles to cope with the refugee influx.
"We call on the Arab and international communities to share this unprecedented burden with Lebanon; before this explosive situation takes on global proportions," said Derbas, as quoted in the UNHCR statement.
The strain has been particularly felt across the public sector, with health and education services, as well as electricity, water and sanitation affected.
The humanitarian appeal for Lebanon "is only 13 percent funded," even as the needs of a rapidly growing refugee population become ever more pressing, the UNHCR said.
Half the refugees are children, with the vast majority not attending school.
"The number of school-aged children is now over 400,000, eclipsing the number of Lebanese children in public schools. These schools have opened their doors to over 100,000 refugees, yet the ability to accept more is severely limited," it added.
Because of the dire economic situation their families endure, many children are now working, "girls can be married young and the prospect of a better future recedes the longer they remain out of school," it said.
Unlike Jordan and Turkey, which are also hosting massive numbers of Syrian refugees, Lebanon has not set up official camps.
Tens of thousands of families live in insalubrious informal settlements dotted around the country, many of them near the restive border with Syria.
With the conflict in Syria growing more brutal by the day, and with no solution on the horizon, the number of people arriving in Lebanon is rising exponentially, with UNHCR registering "more than one person a minute".
Syria's war began as a peaceful uprising demanding political change in Arab Spring-inspired protests, but it morphed into a bloody insurgency after Assad's regime launched a brutal crackdown against dissent.
The conflict has killed more than 150,000 people, according to the Syrian Observatory for Human Rights, while half of the population is estimated to have fled their homes.