Islamic State group attacks killed at least 30 pro-government forces and soldiers in the Syrian desert, a war monitor said Wednesday, in one of the deadliest such assaults this year.

The Britain-based Syrian Observatory for Human Rights said there had been "30 dead, four of them soldiers and 26 from the National Defence Forces, in simultaneous attacks carried out by the Islamic State group on Wednesday morning on checkpoints and military positions" in the Syrian desert.

The attacks took place in locations between Raqa, Homs and Deir Ezzor, added the Observatory, which has a vast network of sources on the ground.

Observatory chief Rami Abdel Rahman warned the toll could rise, citing an unspecified number of wounded, some in serious condition.

IS proclaimed a "caliphate" in June 2014 across swathes of Syria and Iraq and launched a reign of terror.

It was defeated territorially in Syria in 2019 but its remnants continue to carry out deadly hit-and-run attacks and ambushes, particularly from desert hideouts.

Syria's war broke out after President Bashar al-Assad's government crushed peaceful pro-democracy protests in 2011. It has since drawn in foreign powers and global jihadists.

The conflict has killed more than 500,000 people and driven half of the country's pre-war population from their homes.