An Afghan man wearing an army uniform killed a NATO soldier in eastern Afghanistan on Thursday, the military alliance said in a statement.
"The scene of the incident is secure and the suspected gunman has been killed," the NATO statement said. It did not give any further details, dpa reported.
An Afghan official said the incident took place in Paktia.
On Saturday, an attacker wearing an Afghan army uniform shot dead three NATO soldiers in Gardez city, the provincial capital of Paktia province.
Last year, more than 60 NATO soldiers and contractors were killed by Afghan security forces in the "green-on-blue" incidents, prompting serious concerns for the coalition.
Meanwhile, four Afghan army soldiers were kidnapped by suspected Taliban insurgents in the northern province of Kunduz.
District governor of Khanabad, Hayatullah Amiri, told dpa that the four soldiers were in civilian clothes and were taken early Thursday from his district.
"Taliban stopped the public bus coming from Taloqan to Kunduz city. They searched for people's identification cards and found four people working for the national army," Amiri said.
It was not clear where the soldiers were taken. The Taliban have not confirmed the incident.