On Wednesday a Nato airstrike left five Afghan soldiers dead and two others wounded in the Andar district of Ghazni province.
The Afghan soldiers were launching an ambush before dawn against insurgents reportedly on the move when Nato aircraft began firing on them without warning, an Afghan defence ministry official said.
Nato blamed the attack on a communication error.
A coalition statement, also issued on Friday, said a joint investigation determined that the Afghan army unit gave the wrong location to international forces when it reported it would be operating in Ghazni.
The back-to-back incidents come as international troops try to gain the trust of the Afghan people and improve coordination with Afghan security forces in hopes of handing over more responsibility for security to them nearly nine years into the war.