WASHINGTON — The Department of Homeland Security on Monday reassigned the acting director of the Transportation Security Administration and ordered the agency to revise its security procedures after screeners at airport checkpoints failed to detect weapons and other prohibited items 95 percent of the time in a covert test.

Jeh Johnson, the secretary of Homeland Security, which oversees the T.S.A., said that he took the findings of the investigation by the department’s inspector general “very seriously.” He called on the T.S.A. to retrain airport security officers, retest screening equipment and increase its use of covert testing in airports.

In the investigation, undercover agents were able to get prohibited items through security checkpoints in 67 of 70 instances, according to ABC News, which first reported the findings.

Melvin Carraway, the acting administrator of the T.S.A., was replaced by the acting deputy, Mark Hatfield. In April, President Obama nominated Vice Adm. Peter Neffenger of the Coast Guard to be the agency’s next administrator.