At least 15 Afghan soldiers were killed when Taliban fighters attacked their army base in the southern province of Kandahar.
The Defence ministry said it was the second such assault on western-backed forces this week.
The attack in Shah Wali Kot district late Thursday came just three days after 10 afghan soldiers were killed when Taliban militants stormed another base in the same area.
The assault, mounted by hundreds of insurgents, highlights a growing Taliban offensive in Kandahar, where security has relatively improved in recent years under the leadership of police chief and regional strongman General Abdul Raziq.
The Taliban claimed responsibility for the Kandahar attack as their annual spring offensive intensifies and the insurgency expands more than 15 years after they were toppled from power in a US-led invasion.