KABUL — Afghanistan's Defense Ministry says hundreds of soldiers have been discharged or detained as part of an investigation into the backgrounds of its military forces after a surge in insider attacks against foreign troops.

Ministry spokesman Mohammad Zahir Azimi did not provide any other details or specific numbers on Wednesday. He said many of the troops had been discharged from the military because they had suspect documents, either incomplete or forged.

Many Afghans seek to join the army or police to secure stable employment.

Azimi added that the investigation began about six months ago and promised more details next week.

On Sunday, the deputy commander of the U.S.-led NATO coalition also confirmed that a number of soldiers were suspended but also did not provide a number.