DOMZIN, Iraq — Former Syrian soldiers who've escaped to northern Iraq are telling grisly stories of how their units executed unarmed civilians for demonstrating against the Assad regime and staged mass reprisals when residents shot back, on one occasion lining up and shooting 30 defenseless civilians.

The former soldiers — Syrian Kurds who've crossed the mountainous border into Iraq's Kurdistan region in small groups over the past three months, a group that now totals well more than 400 — also brought tales of colleagues being shot for not firing on civilians. One former special-forces noncommissioned officer even said he suspected that other government troops had orchestrated an ambush his unit endured, in an effort to motivate the unit to kill civilians.

Members of a special United Nations commission of inquiry said they'd heard many reports of soldiers being shot for not shooting civilians but that they hadn't been able to confirm them. The U.N. investigators said they hadn't heard reports of government-staged ambushes against its own forces.

Reports of brutality against Syrian civilians in the year since the government of President Bashar Assad has moved aggressively against demonstrators demanding Assad's removal are nothing new. But those accounts have come largely from members of the opposition or refugees, who've told investigators of them.

The testimonies of the former soldiers, however, are the first accounts from individuals who were serving in military units that allegedly carried out the atrocities. They provide new substance to the U.N.'s accusations that the Syrian government may be guilty of "crimes against humanity" for its brutal suppression of the anti-Assad uprising.

With foreign reporters largely banned from Syria, there's no way to confirm much of what the former soldiers say. But the accounts of more than a dozen deserters whom McClatchy interviewed offered a consistent tale of men in uniform who at first tried to avoid carrying out their orders and then fled their country rather than continue to open fire on what they considered to be innocent civilians.

None of the deserters said they intended to return to Syria to take up arms against Assad.

One of the most detailed accounts came from a former soldier who identified himself as Master Sgt. Maxim Kawa, a pseudonym he adopted to protect his family, still in Syria.

Kawa, who said he was 26, said he was based in Homs with the Syrian special forces, an elite unit that was deployed repeatedly in the heartland of the uprising to suppress civilian protesters starting last May. Kawa said the unit's mission was to protect and clear the way for one of Syria's 16 security services to seize civilian resisters, but that his unit's members also were ordered to execute civilians. This they did until something snapped, and top officers were sent in to give them a two-day "re-education" course.

Kawa said the unit mounted repeated assaults on civilian protesters in Baba Amr, a part of Homs that the army retook in February after 26 days of artillery bombardment, in the towns of Rastan, about 12 miles from Homs, and Tel Kalakh, on Syria's border with Lebanon.

Kawa's unit occupied Rastan for eight days last May, losing one soldier to an armed local. "Our officers told us that we must take revenge for our friends," Kawa said. "They pushed us to kill civilians."