The month of March was the deadliest in Syria's two-year conflict, with more than 6,000 people killed, a monitoring group said on Monday.
"At least 6,005 people were killed in March. A total of 2,080 were civilians, among them 298 children aged under 16. Another 291 fatalities were women," said Syrian Observatory for Human Rights director Rami Abdel Rahman.
Most rebel fighters in Syria's conflict are civilians who have taken up arms to fight against forces loyal to President Bashar al-Assad.
Of the total killed in March, at least 2,074 were rebel fighters, among them 86 former Syrian army soldiers who defected and joined the insurgency, Abdel Rahman said.
Also among them were 588 rebels whose names the group could not verify, including "a large number of non-Syrian fighters," said the Observatory, which relies on a network of activists, lawyers and medics for its information.
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Also killed were 1,464 troops loyal to the Assad regime, Abdel Rahman told AFP.
The Observatory also reported the deaths of 387 people whose identities were impossible to verify.
"We believe the actual numbers of army troops and rebels killed in March were higher," said Abdel Rahman, adding both sides in Syria's war try to conceal the full extent of casualties to boost morale.
The United Nations said in January that more than 70,000 people have been killed in Syria since March 2011.
But the Observatory said on Monday that according to its count, so far 62,594 people have been killed in the conflict, including at least 30,782 civilians, 15,283 troops, and 14,302 rebels.
The Observatory uses reports from the field and footage of bodies to document fatalities. It also works to record the victims' names, though Abdel Rahman admits that is not always possible.