Several Syrian soldiers were killed on Thursday after jihadis from the extremist "Islamic State" (IS) group attacked the bus they were traveling on in eastern Deir Ezzor province, a Britain-based monitor said on Friday.

The Syrian Observatory for Human Rights said the attack killed "23 soldiers and wounded more than 10 others," while many others were missing. Some of the wounded were in critical condition, according to the Observatory, which gathers information from a wide network of sources inside Syria.

The group later claimed responsibility for the attack on the Telegram messaging app.

IS has recently stepped up its attacks in the north and northeast, using hideouts in the Syrian desert as its bases after losing the last swathes of territory it controlled in 2019.

Earlier this week, the Observatory reported that an IS attack in the group's former stronghold of Raqqa province had killed 10 Syrian soldiers and pro-government fighters.

Fraught situation

The regime of Syrian President Bashar Assad now once more controls two-thirds of the country after a yearslong civil war that had its roots in pro-democracy protests in 2011. The conflict that erupted after those protests were brutally suppressed by the government has drawn in a large range of protagonists, with notably Russia supporting Assad and Turkey on the side of the rebels.

Despite the government's military offensives, large parts of the country are still under the control of rebels, jihadis and the Kurdish-led Syrian Democratic Forces (SDF). The northwestern province of Idlib and adjoining parts of northern Hama and western Aleppo provinces are now the last remaining opposition stronghold.

The conflict, for which no political solution is in sight, has left an estimated 500,000 people dead.

tj/sms (AFP, dpa, Reuters)