Updated

Jihadi-led rebel fighters in Syria killed at least 190 civilians and abducted more than 200 during an offensive against pro-regime villages, committing a war crime, an international human rights group said Friday.

The Aug. 4 attacks on unarmed civilians in more than a dozen villages in the coastal province of Latakia were systematic and could even amount to a crime against humanity, Human Rights Watch said in a 105-page report based on a visit to the area a month later.

Witnesses said rebels went house to house, in some cases executing entire families and in other cases killing men and taking women and children hostages. The villagers belong to the minority Alawite sect, an offshoot of Shiite Islam which forms the backbone of President Bashar Assad's regime -- and which Sunni Muslim extremists consider heretics.

One survivor, Hassan Shebli, said he fled as rebels approached his village of Barouda at dawn, but was forced to leave behind his wife, who was unable to walk without crutches, and his 23-year-old son, who is completely paralyzed.

When Shebli returned days later, after government forces retook the village, he found his wife and son buried near the house and bullet holes and blood splatters in the bedroom, the New York-based group said.

The findings are bound to feed mounting Western unease about the tactics of some of those trying to topple Assad and about the growing role of jihadi rebels, including foreign fighters linked to al-Qaida.

U.N. war crimes investigators have accused both sides in Syria's civil war, now in its third year, of wrongdoing, though they said earlier this year that the scale and intensity of rebel abuses hasn't reached that of the regime.

The new allegations of rebel abuses come at a time when the regime is regaining some international legitimacy because of its apparent cooperation with an internationally mandated program to destroy Syria's chemical weapons stockpile by mid-2014.

Lama Fakih of Human Rights Watch said the rebel abuses in Latakia "certainly amount to war crimes," and may even rise to the level of crimes against humanity.

The group said more than 20 rebel groups participated in the Latakia offensive.

Five groups, including two linked to Al Qaeda and others with jihadi leanings, led the campaign, which appeared to have been funded in part by private donations raised in the Persian Gulf, the report said.

Human Rights Watch appealed to the Gulf states to crack down on such money transfers. It also urged Turkey, a rear base for many rebel groups, to prosecute those linked to war crimes and restrict the flow of weapons and fighters. The Western-backed Syrian opposition must cut ties with the groups that led the Latakia offensive, the report said.

Most of the alleged attacks on civilians occurred on Aug. 4, said the group. The campaign began with rebel fighters seizing three regime posts and then the villages. After the regime positions fell, no pro-government troops were left in the Alawite villages. It took government forces two weeks to recapture all the villages.

Human Rights Watch said at least 67 of the 190 civilians slain by the rebels were killed at close range or while trying to flee. There are signs that most of the others were also killed intentionally or indiscriminately, but more investigation is needed, the group said.

The rebels seized more than 200 civilians from the Alawite villages, most of them women and children, and demanded to trade the hostages for prisoners held by the regime.

The HRW report said the rebel groups that led the offensive included Jabhat al-Nusra and the Islamic State in Iraq and the Levant, both linked to Al Qaeda; Ahrar al-Sham; Jaish al-Muhajireen wal-Ansar; and Suqqor al-Izz.