The Syrian government said Thursday that its preliminary investigation into the massacre of 108 civilians in the village of Houla proved that security forces were not responsible.

The announcement came as Houla residents reported being targeted by renewed mortar and heavy machine-gun fire from Syrian army positions, and activists said that as many as 15 factory workers had been executed at a Syrian army checkpoint.

The fresh reports of violence suggested that the recent surge in international condemnation of the Syrian government in the wake of the Houla killings has done little to quell the violence.

Brig. Gen. Qassem Jamal Suleiman, head of the investigative committee, said at a news conference in Damascus that 600 to 800 men from “armed terrorist groups” had carried out last Friday’s killings after attacking Syrian forces earlier in the day.

He said all the victims belonged to families that “refused to oppose the government and were at odds with the armed groups.”

Foreign Ministry spokesman Jihad Makdissi said the massacre was carried out by people who wanted to trigger international military intervention in Syria. “The Syrian army could not have committed a massacre like this,” he said at the news conference. “The international community is putting a spotlight on Houla because this is an area where there is a certain sect . . . in order to prove that what is happening in Syria has become a sectarian civil war.”

Residents of Houla, a collection of Sunni villages outside the city of Homs, say the killings were carried out by pro-government militias known as the shabiha that came from nearby villages populated by Alawites, members of a minority Shiite sect to which the ruling Assad family belongs. U.N. monitors who are in the country to observe a tenuous cease-fire have confirmed the deaths and say 49 children and 34 women were among the victims.

A U.N. statement Sunday blamed the Syrian government for the deaths, signaling the harshest international condemnation of President Bashar al-Assad’s regime since the uprising against his rule began 14 months ago.

Activists posted video on YouTube purporting to show evidence of fresh executions by government forces Thursday. The footage showed the bloodied and abused bodies of about a dozen men, who apparently had been stopped at a Syrian army checkpoint outside the town of Buwayda, also in the troubled province of Homs.

The assertions could not be independently verified because the Syrian government denies most foreign journalists access to the country.