The Defense Ministry said Wednesday its probe had found no organizational cover-up of troop activity logs related to a controversial deployment to war-torn Iraq between 2004 and 2006.

The ministry initially claimed that the logs had been discarded in response to a request for their disclosure by an opposition lawmaker in February 2017. However the logs were discovered later that year, prompting the ministry to investigate.

Based on the findings, the ministry reprimanded a total of 17 people, including Vice Defense Minister Katashi Toyota, who was held responsible for the logs' insufficient supervision.

It was not until March this year that Defense Minister Itsunori Onodera learned that the activity logs still existed, a year after their discovery. The Joint Staff Office confirmed the existence of the logs in February.

In February 2017, then Defense Minister Tomomi Inada requested that the Self-Defense Forces look for the logs, but the SDF replied they no longer existed, raising the question of whether Inada's instruction was shared among her subordinates.

Recently, there have been a series of revelations regarding the mishandling of government documents by ministries. The Defense Ministry has also been under fire for its handling of activity logs for SDF troops participating in a U.N. peacekeeping mission in South Sudan.

"It is an incident that could have affected civilian control, resulting from a failure by the ministry and the SDF to follow the minister's instructions," Onodera told reporters. Prime Minister Shinzo Abe told him to take measures to ensure such a problem will not be repeated, the defense chief said.

Opposition parties have alleged a cover-up. Japan sent roughly 5,500 Ground Self-Defense Force troops to Iraq from January 2004 to July 2006 to provide medical aid and repair infrastructure in Samawah, an overseas deployment that some claimed was not in line with the nation's war-renouncing Constitution.