Last month, a Saudi officer who was undergoing pilot training at the Naval Air Station Pensacola, opened fire in a classroom, killing three US sailors and wounding eight other people before he was shot dead. The Pentagon later announced the termination of the operational training for all Saudi servicemen undergoing training in the United States for an indefinite period.

"In the wake of the Pensacola tragedy, the Department of Defense restricted to classroom training programs foreign military students from Saudi Arabia while we conducted a review and enhancement of our foreign student vetting procedures. That training pause is still in place while we implement new screening and security measures," Defense Department spokesman Lt Col Robert Carver was quoted as saying by CNN.

According to the media outlet's sources, some of the trainees were accused of having links with extremist movements, others of possession of child pornography.

Representatives of the FBI and the US Department of Justice declined to comment, the CNN added.