Suicide car bomb kills four at Kurdish checkpoint in Syria

A suicide car bomb attack killed four people overnight at a Kurdish security checkpoint in northeast Syria, the Syrian Observatory for Human Rights monitor said on Tuesday.

The attack comes as Kurdish forces from the People's Protection Units (YPG) spearhead the fight for the Islamic State (IS) group's Syrian stronghold Raqqa as part of a US-backed alliance.

The Britain-based monitor said the blast hit a checkpoint manned by the Asayesh security forces in Hassakeh province, around 20 kilometres (12 miles) from the town of Ras al-Ain.

At least two of the dead were Asayesh members, the monitor said, while the identities of the other two were not yet confirmed.

Syrian state television also reported the blast on Tuesday and said four people were killed.

Kurdish-controlled areas have come under regular bomb attack, with IS often claiming responsibility. There was no immediate claim for Tuesday's incident.

The US-backed Syrian Democratic Forces, which is dominated by Kurdish forces, is battling IS for control of the group's Syrian stronghold Raqqa.

The militia now controls around 35 percent of the city, according to the Observatory.

More than 330,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests. The Baath regime, in power since 1963 and led by President Bashar al-Assad, responded with military force to peaceful protests demanding democratic reforms during the Arab Spring wave of uprisings, triggering an armed rebellion fuelled by mass defections from the Syrian army.
 
According to independent monitors, hundreds of thousands of civilians have been killed mostly by the regime and its powerful allies, and millions have been displaced both inside and outside of Syria.

The brutal tactics pursued mainly by the regime, which have included the use of chemical weapons, sieges, mass executions and torture against civilians have led to war crimes investigations.