A report by a Syrian thinktank estimates that 470,000 people have died in the civil war, nearly double recent UN estimates, portraying a "shattered and fragmented" country where 69 per cent of people are living in extreme poverty.
"The country faces a human catastrophe reflected in the dramatic drop in life expectancy at birth from 70.5 years in 2010 to an estimated 55.4 years in 2015," according to the Syrian Centre for Policy Research (SCPR).
SCPR calls itself an independent non-profit group, but critics say the Damascus-based centre is loyal to the regime of Syrian President Bashar al-Assad.
The Syrian Observatory for Human Rights, a pro-opposition monitoring group based in Britain, estimated Thursday that the conflict has claimed the lives of nearly 270,000 people.
The head of the Observatory, Rami Abdel-Rahman, told dpa that the death toll has reached 269,617 people, including 78,586 civilians.
Meanwhile, SCPR said in its report released in Beirut that about 11.5 per cent of Syria's population has been killed or injured since 2010, nearly half are displaced, and the school age non-attendance rate is 45.2 per cent.
Some 35 per cent of people are living in abject poverty, unable to meet basic food needs, it said, adding that poverty levels "increase dramatically in conflict zones and besieged areas."
Accumulated economic losses reached an estimated 254.7 billion dollars by the end of 2015, equivalent to 468 per cent of Syria's gross domestic product in 2010.
"During 2015, the Syrian economy became more shattered and fragmented, mainly dominated by the fighting subjugating powers," the report said.
"Each of these powers is rebuilding its own independent economic entities and foundations in which resources are being reallocated to serving its objectives and creating incentives and drawing loyalty among their narrow group of followers against people's needs and aspirations," it said.
The Syrian conflict started in March 2011 with peaceful pro-democracy protests against al-Assad's regime.