Syrian authorities have arrested a relative of President Bashar Assad, the state news agency said Monday, two days after protesters called for the man's punishment over his suspected killing of an army officer in a traffic dispute.

Hundreds of Syrians staged a rare protest on Saturday evening in the coastal city of Latakia, a stronghold of Assad and his Alawite sect, to demand the execution of Suleiman al-Assad, the son of the president's cousin, Hilal.

State news agency SANA said authorities "arrested Suleiman Hilal al-Assad and transferred him to the relevant parties." It gave no further details.

Syria's state media did not reported the protest, the traffic incident or the reported killing.

Details of what happened vary.

However, according to the Britain-based Syrian Observatory for Human Rights and Assad's supporters on social media, Suleiman al-Assad was angered when Col. Hassan al-Shaikh, who was in a car with his family, overtook his vehicle in a Latakia street, and so shot him dead nearby shortly afterwards.

In a video posted on social media, protesters at Saturday's rally chanted: "The people want the execution of Suleiman." They also chanted slogans in support of the president.

The arrested man's father, Hilal al-Assad, was killed in battles with Islamist insurgents last year.

In Syria's four-year-old civil war, Alawites, who make up roughly 10 percent of the 23 million population, have largely backed Assad against mainly Sunni Muslim insurgents.

But opposition activists say dissent has been growing within Assad's Latakia regional heartland largely due to a high death toll among Alawite fighters and civilians — tens of thousands — in the conflict, as well as official corruption.