BEIRUT: Fifteen soldiers died Sunday in an Islamic State group attack on an army bus in the central Syrian desert, a war monitor said.

State news agency SANA had reported 13 dead "including officers" and 18 wounded.

IS cells "attacked a military bus" in the Palmyra desert, "killing 15 soldiers and wounding 18 others", the British-based Syrian Observatory for Human Rights said.

The death toll could rise as most of the soldiers were "seriously wounded", said the Observatory, which relies on a network of sources across the country.

IS did not immediately claim responsibility for the attack.

Rockets fired at US base in east Syria: monitor

The Observatory said 61 pro-regime soldiers and Iran-affiliated militiamen had been killed in IS attacks in the desert of Syria since the start of the year.

Despite the fall of IS's "caliphate" in 2019, the group continues to launch deadly attacks from hideouts in the Syrian desert, which extends from the outskirts of the capital Damascus to the Iraqi border.

In early January, nine Syrian soldiers and allied fighters were killed in a similar attack on a military convoy in Syria's east.

On January 20, IS fighters launched their biggest assault in years, attacking a prison in the Kurdish-controlled northeast Syrian city of Hasakeh, aiming to free fellow jihadists.

Almost a week of intense fighting left more than 370 dead, according to the Observatory.