The UNHCR said on Thursday that Lebanon had the world's "highest per capita concentration of refugees" and urgently needed boosts in funding.
A current humanitarian aid appeal for Lebanon was only 13 percent funded, the agency said, adding that 2,500 new refugees entered Lebanon daily – more than one person per minute.
United Nations High Commissioner for Refugees Antonio Guterres said the impact on Lebanon – a small country of 4.5 million people – was "staggering."
The influx had severely stretched Lebanon's health and education sectors as well as its electricity, water and sanitation services. Lebanon had shown "striking generosity" but was "struggling to cope," he said.
Children make up half
Half of the Syrian refugees - living in tented settlements and makeshift shelters (pictured) in Lebanon - are children, according to the UNHCR. Only around 100,000 of them are attending public schools.
The majority of school-aged Syrian refugees in Lebanon lacked schooling, with many forced to work. Girls were often off married young.
In Beirut, UNHCR regional representative Ninette Kelley said the self-immolation by a Syrian refugee mother in Lebanon last week was a "telling reminder of the consequences of the Syrian emergency."
Mariam al-Khawli is being treated for 70 percent burns to her body after an unexplained cut in aid funding to her family, including her disabled husband and three children suffering from blood ailments.
Khawli told Reuters Wednesday: "We got hungry … but they burned my heart before they burned my body. They burned my heart from the inside."
Kelley said UN teams in Lebanon gave aid to the most vulnerable first and made regular checks on families who were not covered.
"We simply do not have enough [funding]," Kelley said.
Syria's three-year civil war has also left some 600,000 refugees registered in Jordan and around 670,000 in Turkey.
In a further sign of Lebanon's attempt to cope with the spillover from Syria's war, Lebanese troops moved into a restive Sunni area of the northern Lebanese city of Tripoli on Wednesday.
On Tuesday, the army had entered the adjacent Alawite precinct of Jabal Mohsen.
Syria's conflict has split Lebanon between Alawites who tend to back Syrian President Bashar al-Assad and Sunnis who tend to back those opposing his regime.
Sectarian clashes between fighters of two Tripoli neighborhoods in the Mediterranean port city claimed at least 30 lives in March.
Tripoli residents said Wednesday they hoped the army's bid to cap sectarian tensions would restore a semblance of urban normality.
High toll in 3-year war
According to the Britain-based Syrian Observatory for Human Rights, Syria's three-year civil war has claimed at least 150,000 lives.
It said on Tuesday its death count included more than 51,000 civilians and nearly 8,000 children.
In addition, at least half a million Syrians had been left wounded.
An additional 17,000 people were missing and "tens of thousands" were held in regime prisons, the observatory said.
Aid agencies, including the International Red Cross, have repeatedly called for protected field access for aid deliveries. Forty percent of Syria's hospitals have been destroyed, according to the UN.
Syria's economic output has fallen 45 percent since the uprising's start in 2011.#
ipj/slk (AFP, AP, Reuters)