At least five people were killed by a truck bomb near a military court in the city of Gardez in the eastern Afghan province of Paktia on May 14, officials said.
"Dozens of civilians are feared to be dead and wounded," said Tariq Arian, an Interior Ministry spokesman.
Emal Khan Momand, a military spokesman in Paktia Province, said the attack was carried out with a truck packed with explosives.
Five people were killed and 14 were wounded, Momand said.
In a statement, Taliban spokesman Zabihullah Mujahid said the militant movement was responsible for the attack.
Arian blamed the militant Haqqani network, which has ties to Taliban militants.
The blast comes after gunmen attacked a maternity hospital in Kabul, killing 24 people, including new mothers and newborn babies, on May 12. A suicide blast claimed by the Islamic State militant group at a funeral in eastern Nangahar on the same day killed 32 people.
The Taliban denied any involvement in those attacks, which came amid a resurgence in violence that threatens to unravel a landmark agreement between the militant movement and the United States meant to put an end to the 18-year conflict.