The Syrian presidency announced on Telegram that an “independent committee” had been formed to “investigate the violations against civilians and identify those responsible for them”, who would face the courts.
Clashes between the new security forces and loyalists of the former Government erupted on Thursday, after earlier tensions.
The violence is in the heartland of the Alawite minority to which Assad belongs and has escalated into reported mass killings.
Earlier Sunday, Syria’s interim leader Ahmed al-Sharaa had appealed for national unity.
“God willing, we will be able to live together in this country,” Sharaa said from a Damascus mosque.
The fighting has also killed 231 members of the security forces and 250 pro-Assad fighters, according to the Observatory, taking the overall death toll to 1311.
The Interior Ministry said on Sunday that government forces were conducting “sweeping operations” in an area of Tartus province to “pursue the remnants of the toppled regime”.
State news agency SANA quoted a defence ministry source as saying there were clashes in Tanita village in the same area.
An AFP photographer in Latakia city reported a military convoy entering a neighbourhood to search homes.
In Baniyas, a city further south, resident Samir Haidar, 67, told AFP two of his brothers and his nephew were killed by armed groups that entered people’s homes, adding there were “foreigners among them”.
“They gathered all the men on the roof and opened fire on them,” Haidar said.
Defence ministry spokesman Hassan Abdul Ghani said on Saturday the security forces had “reimposed control” over areas that had seen attacks by Assad loyalists.
The mass killings followed clashes sparked by the arrest of a wanted suspect in a predominantly Alawite village, the Observatory said, reporting a “relative return to calm” in the coastal region on Saturday.
The head of the World Health Organisation, Tedros Adhanom Ghebreyesus, said medical facilities had been damaged in the clashes and that the UN agency was “working to deliver medicines and trauma supplies”.
Chief US diplomat Marco Rubio said Syria “must hold the perpetrators of these massacres against Syria’s minority communities accountable”, while Britain’s Foreign Secretary David Lammy said Damascus authorities “must ensure the protection of all Syrians and set out a clear path to transitional justice”.
Germany’s foreign ministry said the Syrian authorities had “a responsibility to prevent further attacks”.
In Jordan, Syria’s Foreign Minister Asaad al-Shaibani said that, “Anyone involved in this matter will be referred to the judiciary.”
Sharaa’s Islamist group Hayat Tahrir al-Sham (HTS), which led the toppling of Assad in December, has its roots in the Syrian branch of Al-Qaeda and remains proscribed as a terrorist organisation by many governments, including the United States.
Since the rebel victory, it has vowed to protect Syria’s religious and ethnic minorities.
The new Government has received diplomats from the West and its neighbours. It is seeking an easing of sanctions with investment to rebuild a country devastated by 13 years of civil war under the repressive rule of Assad.
Sharaa has said Syria must be built “on the rule of law”.
The UN’s Turk said in a statement there had been a “continuous spike in hate speech both online and offline” in Syria and insisted there was an “urgent need for a comprehensive transitional justice process”.
Israeli Foreign Minister Gideon Sa’ar, speaking to German newspaper Bild, said Europe “must wake up” and “stop granting legitimacy” to the new Syrian authorities who he insisted were still jihadists.
The Alawite heartland has been gripped by fear of reprisals for the Assad family’s five-decade rule which included widespread torture and disappearances.
Social media users have shared posts documenting the killing of Alawite friends and relatives.
The Britain-based Observatory, which relies on a network of sources in Syria, reported multiple “massacres” in recent days, with women and children among the dead.
The Observatory and activists released footage showing dozens of bodies piled outside a house. Other videos appeared to show men in military garb shooting people at close range.
AFP could not independently verify the images or accounts.
During a sermon in Damascus, the Greek Orthodox Patriarch of Antioch John X said Christians were among those killed and called on Sharaa to “put a stop to these massacres... and give a sense of safety and security to all the people of Syria, regardless of their sect”.
Later on Sunday, Syrian security forces fired into the air to disperse rival protesters in Damascus who engaged in physical altercations over the killings in the coastal areas.
- Agence France-Presse
