With no end in sight to Syria's civil war, the number of people who have fled to neighboring countries has surpassed 4 million, according to United Nations figures released Thursday.
"This is the biggest refugee population from a single conflict in a generation," U.N. High Commissioner for Refugees Antonio Guterres said in a statement. "It is a population that needs the support of the world but is instead living in dire conditions and sinking deeper into poverty."
The last time a conflict produced so many refugees was during the 1990s civil war in Afghanistan, when the number of people driven from their country exceeded 4.6 million.
The massive exodus has stretched the resources of Syria's neighbors to the breaking point.
"Worsening conditions are driving growing numbers towards Europe and further afield, but the overwhelming majority remain in the region," Guterres said.
More than 24,000 people arrived in Turkey from Tal Abyad and other parts of northern Syria in June alone, driving that country's refugee population to more than 1.8 million, the largest in the world, the U.N. said.
A further 1.1 million Syrian refugees are in Lebanon; 629,000 in Jordan; nearly 250,000 in Iraq; 132,000 in Egypt; and 24,000 elsewhere in North Africa.
The figures released Thursday do not include more than 270,000 Syrians who have applied for asylum in Europe, often after undertaking costly and dangerous journeys in smuggling ships that ply the Mediterranean Sea. Thousands of others have been resettled elsewhere in the world.
The Syrian conflict, now in its fifth year, also has displaced 7.6 million people inside the country, according to U.N. estimates.
Funding for programs that support the refugees has not kept pace with the scale of the crisis. As of late June, less than a quarter of the $5.5 billion that UNHCR estimates will be needed in 2015 had been raised.
"This means refugees face tough new cuts in food aid and struggle to afford lifesaving health services or send their children to school," the agency said in the statement.
The increasingly dire conditions are forcing Syrian families to put their children to work.
Nearly half of refugee households in Jordan rely on income generated by a child, according to a report issued last week by the U.N. Children's Fund and the aid group Save the Children. Child marriages are also on the rise, along with children begging in the streets.
"We cannot afford to let them and the communities hosting them slide further into desperation," Guterres said.