Police chief Dawlat Khan said the soldiers were killed when around 200 Taliban fighters attacked a remote district headquarters at Terwah on Sunday evening.
However, no one has yet claimed responsibility for the killings.
The attack came a day after six Afghan soldiers were killed in the same area.
The clash near the Pakistani frontier on Saturday was the latest cross-border insurgency blamed on the Taliban and al-Qaida.
The fighting in Paktika is likely to trigger further protests from Kabul, which has blamed Islamabad for allowing fighters to launch attacks from Pakistani soil.
Afghan-Pakistan relations have soured in recent months over Kabul's accusations that Pakistan is allowing the Taliban and other groups to launch attacks on Afghan territory.
Pakistan, which was the main backer of the Taliban government until the September 11 attacks on the United States, denies the accusations.