"At least 31 people, including regime troops, were killed when a man detonated a truck laden with explosives at a checkpoint near an agricultural vehicles company on the road linking Hama to Salamiyeh," AFP quoted the Syrian Observatory for Human Rights as saying.
The Britain-based watchdog said the death toll was likely to rise, as "there are dozens of wounded, some of them in critical condition".
State television had earlier reported multiple casualties from a bombing in Hama without giving a more precise casualty toll.
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 foreign-backed militants.
Syria has been gripped by deadly unrest since 2011. According to reports, the Western powers and their regional allies -- especially Qatar, Saudi Arabia, and Turkey -- are supporting the militants operating inside Syria.
According to the United Nations, more than 100,000 people have been killed and a total of 7.8 million others displaced due to the violence.
HH/HH