The Anadolu Agency quoted deputy chairman of the International Refugee Rights Organisation Abdullah Resul Demir as saying that killings had been caused during fighting or in prison.
"The century's most serious human rights violations have been going on in Syria," he said. "However, all the world's countries have turned a blind eye to this situation."
According to Demir, the figure was based on evidence from independent observers between March 2011 and November 2017.
Of the dead, "26,466 of them were children," he said. "Thirteen million people fled their homes and became refugees [and] 3.5 million children were deprived of one of their basic rights, education."
Earlier this week, at least 21 civilians were killed in airstrikes conducted by the Russian forces in Islamic State (IS)-held village in eastern Syria.
A civil defence report claimed that at least 45 civilians lost their lives due to Syrian regime's intense attacks on Eastern Ghouta between November 14 and 17. (ANI)