The car bomb attack comes just three days after hundreds of rebel fighters and civilians were evacuated from Homs
A large car bomb struck the central Syrian city of Homs on Saturday, killing at least 16 people and wounding dozens, state media said.
The blast struck the city's Al-Zahraa neighbourhood, where most residents are Alawite, the same sect to which President Bashar al-Assad belongs.
The Syrian Observatory for Human Rights said 16 people were killed and dozens wounded, adding that some were in critical condition.
The Islamic State group in a statement said it was behind the attack, and said it consisted of a car bombing and a suicide bomber blowing himself up.
The vehicle used in the attack had been carrying at least 150 kilos (330 pounds) of explosives, Barazi added.
In its statement, IS named the bomber as Abu Ahmed al-Homsi, and said he parked the car and detonated it before then activating his explosives belt.
IS said the toll from the attack was more than 25 dead, with 70 wounded.
The monitoring group said a second blast was heard in the city, but its cause was unclear.
"The explosion was terrifying. Body parts were on the ground... It was one of the biggest explosions to hit Homs," a 28-year-old woman working in a neighbourhood coffee shop told AFP.
"The blast left a huge crater, and people were running in every direction in fear of more explosions," she added.
Provincial governor Talal Barazi said the car had been carrying at least 150 kilograms (330 pounds) of explosives.
The attack comes just three days after hundreds of rebel fighters and civilians were evacuated from the city after a deal with Syria's government.
The deal, overseen by the United Nations, would see Homs' last rebel-held neighbourhood, Waer, turned over to government forces in exchange for humanitarian aid for besieged residents.
Once known as the "capital" of Syria's revolution, the city will be under the full control of the government by the end of the January.
The Britain-based Observatory and local activist groups said a UN convoy carrying humanitarian aid was due to enter Waer on Saturday morning, but there was no confirmation from UN representatives in Damascus.
More than 250,000 people have been killed in Syria's conflict since it erupted in March 2011.