Syria: At least 11 soldiers, two civilians killed in an attack near Raqqa

At least 11 Syrian government soldiers and two civilians were killed in an ambush near the remote eastern region of Raqqa on Monday morning, according to the official Sana news agency.

Three more people were wounded in the attack which targeted a bus at 6:30 am local time on a road connecting Raqqa, a former Islamic State (IS) hub now under Kurdish control, and the government-controlled city of Homs. 

The UK-based Syrian Observatory for Human Rights (SOHR) activist monitor reported at least 15 people killed and said the number of casualties could rise.

Sana said a civilian bus was targeted while travelling on the road but SOHR reported that it was a military bus and the attack happened while Syrian government forces were carrying out an operation against IS members.

There was no immediate claim of responsibility for the attack.

Northwestern Syria is the last major stronghold of rebels fighting the Assad government in the country's 11-year-long war. Turkish forces, which back some rebel groups, are deployed in the rebel-held area.

In May, several buses carrying Syrian soldiers were subjected to missile attacks, the last of which killed 10 soldiers and wounded nine others in the north of the country.

The main frontlines in the conflict, which spiralled out of protests against President Bashar al-Assad in 2011, have been largely frozen for several years.