Syria’s interim President Ahmed al-Sharaa has launched an investigation after hundreds of people were killed in fighting between security forces and fighters loyal to ousted President Bashar al-Assad in the coastal cities of Latakia and Tartous.

“We announce the formation of a fact-finding committee regarding the events on the coast and form a higher committee,” al-Sharaa said in an address to the nation on Sunday following days of violent unrest.

The Syrian leader said that the country was confronting attempts to drag it into a civil war. In his speech, al-Sharaa said that “remnants of the former regime” had no choice but to surrender immediately as he vowed to hold accountable “anyone involved in civilian bloodshed”.

The Syrian presidency earlier announced that an “independent committee” had been formed to “investigate the violations against civilians and identify those responsible for them”, adding that the perpetrators would be referred to court.

“The Committee has the right to use whoever it deems appropriate to perform its duties, and submit its report to the Presidency of the Republic within a maximum period of thirty days from the date of issuance of this decision,” the presidency’s statement read.

The fighting began after the pro-Assad fighters coordinated attacks on security forces on Thursday. The attacks spiralled into revenge killings as thousands of armed supporters of Syria’s new leadership went to the coastal areas to support the security forces.

In the face of the clashes, al-Sharaa urged “national unity” as he reassured a crowd at a mosque in his childhood neighbourhood of Mezzeh, in Damascus.

“We have to preserve national unity and domestic peace. We can live together,” the president said.

“Rest assured about Syria, this country has the characteristics for survival … What is currently happening in Syria is within the expected challenges.”

Al-Assad’s overthrow in December ended more than five decades of dynastic rule by his family, which was marked by severe repression and a devastating war that erupted in 2011 after peaceful anti-government protests were met with a brutal security crackdown. Tens of thousands of Syrians were killed and millions were forced to flee the country or displaced internally as Syria descended into war.