At least 43 people have been killed after a suicide bomber blew up a truck laden with explosives at an army checkpoint in Syria's central city of Hama, according to the pro-opposition Syrian Observatory for Human Rights.
Syrian state media confirmed the blast, saying that the man blew himself up inside the vehicle on Sunday on a busy road on the outskirts of the government-held city.
State news agency SANA blamed the attack on "terrorists", the term it uses to describe rebel forces trying to topple President Bashar al-Assad.
The Britain-based Syrian Observatory said 32 civilians were among the dead in the attack on the road linking Hama to the town of Salamiyeh.
SANA said the explosion appeared to have set ablaze a petrol truck nearby, increasing the damage and casualties.
Pictures on Syria TV showed firefighters trying to put out huge fires and black clouds of smoke rising from charred trucks and cars.
Clashes were reportedly ongoing in the area and gunfire could be heard.
On Saturday, activists said a suicide bomber from the self-proclaimed jihadist group Jabhat al-Nusra blew himself up at an army checkpoint in a Damascus suburb.
More than 30 combatants from both sides were said to have been killed in the blast and ensuing clashes.
In the first months after the uprising against Assad's government erupted in March 2011, Hama saw some of the largest demonstrations against his rule.
But in late summer of that year, security forces stormed the city, killing scores of people. They have held a tight grip on the city ever since.
While several other Syrian cities have been engulfed by fighting, Hama has seen only sporadic violence in recent months.
However, the surrounding province has seen some major clashes between troops and rebels.
On the diplomatic front, it was announced on Sunday that a long-delayed Geneva peace conference aimed at bringing together Syria's government and opposition will be held on November 23.