The Syrian conflict has raged for 20 months now, and 40,000 lives have been lost in the process, a monitoring group tells Reuters.

About half of the dead were civilians, while a quarter were rebel fighters and a quarter government troops, says the head of the Syrian Observatory for Human Rights. But "the figure is likely much higher as the rebels and the government lie about how many of their forces have died to make it look like they are winning," Rami Abdelrahman adds.

What's more, "there are 10,000 to 15,000 people who were arrested months ago, so we can't use that number as we don't know if they are dead or alive."