Car bombs and assassinations of army and police officers are common in Benghazi, where troops have clashed regularly with militants from the hardline Islamist group Ansar al-Sharia.
But a suicide bombing would mark a shift in tactics to fit a pattern common in other Islamist struggles in the Middle East, but not in Libya either during or since the uprising that brought down Muammar Gaddafi.
The attack left body parts strewn around the area, said Moetez al-Agouri, a police officer at the post, and the death toll was likely to rise as the authorities identified them.
The attacker blew himself up in front of the military base in Barsis, some 50km outside Benghazi.
"Seven bodies among the victims have been identified but some other bodies were torn to pieces by the explosion," said al-Agouri, who was working at the checkpoint at the time but escaped injury.
Eight people, including civilians, were wounded in the attack on the checkpoint east of Benghazi and were taken to a hospital in the nearby town of Tokra, Agouri said.
"A Toyota truck approached the checkpoint and parked there. There was a young man driving, but when the army troops went to check it out, the vehicle exploded," said Aymen al-Abdlay, a Benghazi army officer.
A witness told the blast had left a large crater in the ground.
Benghazi, the cradle of the 2011 uprising that toppled longtime dictator Gaddafi, has seen a series of attacks in recent months that killed more than 300 people.
The militants are determined to impose their ultraconservative vision of Islam.
All those killed in the attack on Sunday were soldiers, medical sources and security sources said.
Western diplomats worry that the violence in Benghazi will spill over to the capital Tripoli which last month saw the worst fighting in months between militias.
Much of Libya's oil wealth is located in the east where many demand autonomy from the Tripoli government.
Protesters in the east have taken over key ports, blockading much of the North African country's oil exports for months.
The government of Prime Minister Ali Zeidan is struggling to control militias and tribesmen which helped topple Gaddafi in a NATO-backed uprising in 2011 but kept their guns and often resort to force to make political demands.
By Ruchi Singh
reporter
Park Sae-jin
swatchsjp@ajunews.com