A total of 19,666 people were killed this year as a result of the conflict which erupted in 2011 (File)

Syria's nearly eight-year-old conflict saw its lowest annual death toll in 2018 as the regime reasserted its authority over swathes of territory, a war monitor said on Monday.

A total of 19,666 people were killed this year as a result of the conflict, which erupted in 2011, the Syrian Observatory for Human Rights monitoring group reported.

"2018 was the lowest annual toll since the start of the conflict," Observatory chief Rami Abdel Rahman told AFP.

The Britain-based monitor relies on a vast network of sources across Syria to document the war that broke out after the brutal repression of nationwide anti-regime protests in 2011.

The death toll for 2017 stood at more than 33,000 and the highest annual figure was reached in 2014 -- the year the Islamic State jihadist group proclaimed a "caliphate" over large parts of Syria and neighbouring Iraq -- when 76,000 people were killed.

Among those killed in 2018 were 6,349 civilians, 1,437 of them children, Abdel Rahman said.