An al Qaeda affiliate in Syria battled rival rebels across the country's north on Saturday and dozens of bodies piled up in a hospital in an insurgent-held city, a monitoring group said.
A week of infighting between the al Qaeda-linked group, the Islamic State of Iraq and the Levant (ISIL), and other groups including another al Qaeda-affiliated faction has killed hundreds of fighters opposed to President Bashar al-Assad.
Peace talks are planned in Geneva on Jan. 22 between Assad's government and political opponents who demand he step down after almost three years of bloodshed.
But Assad faces little pressure to make concessions after consolidating his grip on Damascus and the centre of Syria in recent fighting, and the main opposition National Coalition has yet to formally decide whether to attend the talks at all.
On Saturday, rebels moved a convoy including tanks and machinegun-mounted trucks to one of the ISIL's strongholds in the northwestern Idlib province in preparation to push the group out, the Syrian Observatory for Human Rights said.
The Britain-based monitoring group, which tracks developments in Syria through a network of military and medical sources, said five rebels were killed when their car hit a landmine outside the town, Saraqeb.
Heavy clashes were taking place around Saraqeb on Saturday, it said.
In Raqqa, the eastern provincial capital which is the only Syrian city under full rebel control, the Observatory said ISIL fighters seized a checkpoint and took over the train station from rival rebels.
In an indication of how heavy the fighting had been in Raqqa in recent days with rival Islamist rebels including some loyal to another al Qaeda affiliate, the Nusra Front, the Observatory quoted medical sources as saying there were dozens of bodies of Islamic State fighters in a hospital.
The ISIL fighters had also dumped the corpses of dozens of their foes in the nearby village of Jazra, to the west of Raqqa, the Observatory said.
The monitoring group said on Friday 500 people had been killed in the rebel fighting which erupted eight days ago.