A car bombing outside a mosque in southern Syria killed scores of people Friday and rebels detonated mines under a hotel in the north, killing 18 loyalists, monitors said.
At least 47 people, including 14 rebel fighters, were killed when the car blew up in front of the mosque in the rebel-held village of Yaduda in the southern Daraa province, said the Syrian Observatory for Human Rights.
Activists blamed regime forces for the attack, said the Britain-based monitor, adding that it expected the death toll to rise because some 150 others were wounded in the explosion, some critically.
On another front, the jihadist Islamic State of Iraq and the Levant (ISIL) executed dozens of people as it was forced by rival rebels to withdraw from five villages including Hreitan, an opposition stronghold in the northern province of Aleppo.
Though rebels once welcomed ISIL in the fight against President Bashar al-Assad, horrific abuses in areas under their domination have turned much of the opposition against them.
Just before their withdrawal from the Hreitan area, ISIL's fighters executed 27 people including 15 Islamist rebels, said the Observatory.
At least 11 more rebels were also reported killed in the fighting.
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In Azaz, elsewhere in Aleppo province, further clashes raged between rebels and ISIL, as the jihadists "beheaded at least four" rival opposition fighters, said the group.
Twenty two others, including two children, were killed in ISIL shelling on Akhtarin, a village in Aleppo province, while 16 members of the jihadist group were killed in the fighting.
Islamist and mainstream rebels opened a front against ISIL on January 3. The jihadists were expelled from the oil-rich eastern province of Deir Ezzor last week.
In the city of Aleppo, at least 18 soldiers and pro-Assad militiamen were killed when Islamist rebels detonated mines under the Carlton hotel used by the army, said the Observatory.
It said the rebels had dug tunnels under and around the Carlton and on Friday morning they set off mines to detonate them.
Fierce battles broke out after the attack, killing an unknown number of rebels, it added.
Insurgents fighting to topple Assad's regime have used this tactic before, both in Aleppo, Syria's one-time commercial capital, and in Damascus province.
More than 136,000 people have been killed overall in Syria's brutal war since March 2011, and millions more have fled their homes.