Death toll of pro-Assad soldiers killed by IS attack on Syria army bus rises to 33

An attack by Islamic State group jihadists on Assad regime forces in Syria's east has killed 33 soldiers, a monitor said Saturday, revising an earlier toll of 26 deaths.

The shooting Thursday evening on an army bus was the extremist group's deadliest attack on pro-Assad forces this year, according to the Syrian Observatory for Human Rights.

Despite losing their last piece of territory in Syria in 2019, IS has maintained hideouts in the vast Syrian desert from which it has carried out ambushes and hit-and-run attacks.

"The death toll from the army bus attack rose to 33 soldiers," said Rami Abdel Rahman, who heads the British-based monitoring group which relies on a wide network of sources inside Syria.

The jihadists surrounded the bus in the desert near Mayadeen, in Deir Ezzor province, and opened fire, the Observatory reported on Friday.

IS still 'active and powerful'

IS claimed the attack later Friday, saying its fighters had carried out an ambush "on two military buses", targeting them "with heavy weapons and rocket-propelled grenades" and setting one on fire, according to a statement from the jihadists' Amaq news agency.

Syrian state news agency SANA said the "terrorist attack" had caused a number of military casualties, citing an army source.

Abdel Rahman said IS "has recently been escalating its deadly military attacks... aiming to cause as many deaths as possible".

By doing so, the jihadists are trying to show that IS "is still active and powerful despite the targeting of its leaders", he told AFP.

Last week, IS announced the death of its leader Abu al-Hussein al-Husseini al-Qurashi, who it said was killed in clashes in northwestern Syria, and named a successor.

IS members in recent weeks have increased their attacks in Syria's north and northeast.

Earlier this week, 10 Syrian soldiers and pro-Assad fighters were killed in an IS attack in the former jihadist stronghold of Raqqa province, the Observatory said.

Syria's war broke after dictator Bashar al-Assad's regime crushed peaceful protests in 2011, leading to foreign intervention and occupation on his behalf from Iran and Russia, as well as a global jihadist insurgency from which IS arose. 

The conflict has killed more than half a million people and driven half of the country's pre-war population from their homes.