* Residents say car explodes near military checkpoint
* Opposition activists deny attack was suicide bombing (Updates death toll, adds clashes, background)
By Suleiman Al-Khalidi
AMMAN, March 3 (Reuters) - An explosion killed seven people and wounded several others in the southern Syrian town of Deraa on Saturday, residents said, in what the Syrian government said was a suicide car bomb attack.
"At least seven people were killed and another eight injured. They happened to be next to the car when it exploded," Saed Jawabra, a Deraa resident said.
Residents said a white Kia car exploded in a park near a military checkpoint in the town's Rawda district, shattering windows in the area and leaving a huge crater.
"A terrorist suicide bomber on Saturday detonated a car he was driving," the Syrian state news agency Sana said, reporting two people had been killed and 20 wounded.
Opposition activists in Deraa denied the explosion was caused by a suicide bomber but did not give an explanation for the attack.
"The explosion shook the whole town and ambulances rushed shortly after. We heard heavy gunfire after that," said Deraa resident Mahmoud Masalmeh.
Reports could not be independently verified as the Syrian government has restricted access to journalists in the country.
Syrian President Bashar al-Assad has been battling a year-long pro-democracy uprising that has become increasingly violent, with army defectors and rebels clashing with government forces around the country.
Rami Abdelrahman, head of the Britain-based Syrian Observatory for Human Rights, said anti-Assad fighters had earlier on Saturday killed six soldiers and wounded nine in the town of al-Herak, south of Deraa.
Residents and activists in the area reported clashes between army defectors and Syrian security units in Herak. They say security reinforcements were sent to the town this morning in the first major security sweep since a similar crackdown in December.
"At least 100 security buses are now stationed near Herak's hospital at the western entrance of the town," an activist said.
"Tanks have shelled a house suspected to be an insurgent hideout."
The United Nations says Syrian security forces have killed more than 7,500 civilians since the revolt began last March. Syria's government said in December that "armed terrorists" had killed more than 2,000 soldiers and police during the unrest. (Writing by Oliver Holmes in Beirut; Editing by Sophie Hares)