At least 115,206 people have been killed in Syria's devastating 30-month conflict, most of them fighters from both sides, a monitoring group said on Tuesday.

"The Syrian Observatory for Human Rights has documented the deaths of 115,206 people from the start of Syria's revolution on March 18, 2011 to September 30, 2013," the Britain-based group said.

Among the dead were 47,206 fighters loyal to President Bashar al-Assad's regime and 23,707 rebels seeking his ouster.

Of those, 28,804 were regular troops, another 18,228 were pro-regime militiamen and "informants" and 174 were members of the pro-Damascus Lebanese Shiite movement Hezbollah, the group said.

On the rebel side, 17,071 were civilians who picked up weapons to join the insurgency, 2,176 were army defectors and 4,460 were either foreign or unidentified fighters killed in battle.

Another 41,533 civilians lost their lives in the war, among them 6,087 children and 4,079 women, said the Observatory.

The group also said it has documented the deaths of an additional 2,760 unidentified victims, who it was not possible to identify as either civilians, rebels or regime forces.

The figures exclude people being held by the regime, who activists have said number in the tens of thousands.

"It also excludes more than 3,000 regime troops held prisoner by the opposition factions," added the Observatory, which relies on a network of activists, lawyers and medics on the ground for its information.

Syria's conflict broke out in March 2011, when peaceful protests calling for political change were met with a massive crackdown on dissent.

It has since developed into an all-out war that has forced millions of people to flee their homes, the United Nations says.