The fifth year of Syria's civil war has been the worst yet, 30 aid agencies said on Friday in a new report entitled, "Fuelling the Fire."
At least 50,000 more people have been killed; 1.5 million more people are in need of humanitarian aid; and almost a million Syrians have been forced to flee their homes, they said.
"The fifth year of the Syria conflict was the worst yet for people as warring parties have continued to wreak havoc, increasingly blocked aid and placed more communities under siege," said the report signed by international and Syrian organizations.
It comes days ahead of the fifth anniversary of the conflict that started with peaceful protests against the regime of President Bashar al-Assad.
A partial truce, brokered by the United States and Russia, has been largely holding in parts of Syria since February 27 despite violations.
The report said some 200,000 houses had been partly or completely destroyed in country, a 20-per-cent increase from 2014.
In 2015, an additional 400,000 children were out of school in Syria, bringing the total to more than 2 million, with a 44-per-cent increase in attacks on the country's hospitals and health facilities.
Signatoriers to the report include Oxfam, the Norwegian Refugee Council, CARE International, and Syrian groups such as The Syrian-American Medical Society (SAMS), Big Heart, and Syria Relief and Development.
"2015 saw the highest number of attacks on hospitals in a single year with at least 112 attacks on medical facilities," said SAMS chief Dr Ahmad Tarakji.
It was harder to deliver aid to Syria's besieged areas in 2015, according to the report.
More than a quarter of a million people have died in Syria's conflict, according to the last UN estimates from August.
More than half of Syria's pre-war population of 22.4 million people has been internally displaced or forced to flee their homeland since the conflict erupted on March 15, 2011.