The attacks came as US President Barack Obama and his Russian counterpart Vladimir Putin discussed a ceasefire deal for Syria on the sidelines of the G20 summit in China.
The Britain-based Syrian Observatory for Human Rights, which maintains a network of contacts inside Syria, put the overall death toll at 53.
At least 38 people were killed in a string of bomb blasts in government-controlled territories.
In the coastal city of Tartus, at least 35 people were killed and dozens of others wounded on Monday, in twin bombings that rocked a checkpoint at the city's entrance, said the report. More than 45 people were injured in two explosions carried out near the Arzouna bridge in Tartous. The province is home to Russia's main naval base in the country.
A motorbike also exploded in the centre of the northeastern city of Hasaka, killing five people including three members of the YPG-affiliated security force known as the Asayish, said the Observatory.
There has been no immediate claim of responsibility for the blasts. Turkey began an operation inside Syria on Aug 24, targeting both IS but also Syrian Kurdish forces that have been a key USA partner in the fight against the jihadist group in Syria. The IS group claimed responsibility for the blast in Hasakeh. The Observatory confirmed a bomb but had no casualty figures.
Another explosion struck a regime checkpoint in the city of Homs, killing two people and injuring seven others, SANA said.
Lots of promises at G-20, few concrete plans
But U.S. and other officials say they plan to bring up Chinese industrial overcapacity and other potentially thorny issues. He noted that talks on Obama's TPP initiative for Asia-Pacific governments and a U.S.
SANA also reported an explosion in the Sabbourah suburb of the capital, Damascus, killing one.
SANA reporter indicated that the terrorist bombing caused material damage to a number of the neighboring houses, in addition to burning a number of cars.
At least 16 of those killed were troops and pro-government militiamen, the Observatory said. The first was a vehicle bomb, the second a suicide belt detonated against the first responders.
The Observatory director Rami Abdel Rahman said the dead in both the Homs and Al-Sabura road attacks were government security forces manning checkpoints.
Internationally, the leaders of the United States and Russian Federation fell short to resolve snags facing an agreement that could bring a ceasefire in the war-torn country.
"Given the gaps of trust that exist, that's a tough negotiation", Mr Obama said after the meeting. He said it was premature to give details about the terms of an agreement, but that the two nations would strengthen cooperation on fighting terrorism.
The leaders told their top diplomats to continue trying to reach an agreement amid "technical" issues having to do with implementation of the agreement.