On Saturday, the Britain-based Observatory said at least 136,227 had been killed by the end of January, one of the country’s bloodiest months since the conflict began in 2011.
There were a total of 47,998 civilians, including more than 7,300 children, among the dead.
The real death toll could be much higher, the group added.
“January was among the bloodiest months since the beginning of the conflict," said Rami Abdel Rahman, the group’s director.
Syria has been gripped by deadly violence since 2011. According to the United Nations, more than four million Syrians will be forced out of their homes in 2014 by the escalating conflict that has already displaced millions.
In early January, Rupert Colville, a spokesman for the UN Office of the High Commissioner for Human Rights, said the world body could no longer verify the sources of information that led to its last death toll of 100,000 people.
“For the time being, we're not updating those figures,” Colville said.
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