An attack by the Islamic State group (IS) killed at least 11 people hunting desert truffles in northern Syria on Sunday, a war monitor said, after the latest such incident.

Between February and April each year, hundreds of impoverished Syrians risk their lives to forage for the delicacy in the vast Syrian desert -- a known hideout for jihadists that is also littered with mines.

Desert truffles can fetch high prices in a country battered by 13 years of war and a crushing economic crisis.

"At least 11 people collecting truffles were killed when IS fighters detonated a bomb as their car passed in the desert of Raqa province in northern Syria," the Syrian Observatory for Human Rights reported.

After the blast, the attackers opened fire, the Observatory added.

Residents were still searching for missing persons, said the Britain-based monitoring group with a network of sources inside Syria, noting that the jihadists kidnapped three other hunters.

IS took control of large swathes of Syria in 2014. A military campaign backed by a United States-led coalition led to the group's territorial defeat in March 2019 but remnants continue to hide in the desert and launch deadly attacks.

The global jihadist group's reach spans beyond Syria, with IS claiming an attack Friday on a concert hall in the Russian capital, Moscow, that left 137 dead.

Earlier in March, 19 truffle collectors were killed in an area of Syria's Raqa, where IS extremists are present, when their vehicle hit a mine, the Observatory said at the time.