"A suicide bomber driving a bomb-laden vehicle blew himself up on Sunday upon arrival at a checkpoint near Aden airport," the official told AFP.
"Four soldiers were killed and two others were wounded," he added, without blaming any group for the attack.
Yemen has been rocked by more than a year of fighting between Iran-backed rebels and pro-government forces, supported by a Saudi-led coalition.
Jihadists have exploited the unrest, with Al-Qaeda and the Islamic State group strengthening their presence in the south, including in Aden which is serving as the government's temporary capital.
On Friday, a car bomb exploded in the port city near a building housing the foreign ministry, without causing casualties, security sources said.
IS claimed responsibility for that attack and also for a suicide bombing on Tuesday in Aden targeting army recruits that killed five.
Forces loyal to President Abedrabbo Mansour Hadi have launched operations against jihadists in recent weeks, backed by the firepower of the Arab coalition.
Late yesterday, five Al-Qaeda suspects were killed in coalition air strikes on two vehicles carrying jihadists in Jaar, a town in the southern province of Abyan, security officials said.
Pro-government forces on Friday expelled Al-Qaeda fighters from Huta, another provincial capital close to Aden, and arrested 49 people suspected of being militants, security officials said.
The United Nations has raised the alarm over the growing influence of Al-Qaeda in Yemen and the mounting civilian toll from coalition air strikes as it pushed all sides to come to the negotiating table for talks to be held in Kuwait tomorrow.
A nearly week-long ceasefire, between the rebels on one side and the government and Arab coalition on the other, does not apply to jihadist groups.
