Second border officer on leave amid review

A second high-ranking Australian Border Force officer is believed to have taken extended leave pending an inquiry into his personal conduct.

Immigration officials are tight-lipped on the senior uniformed officer's absence, just days after it emerged ABF commissioner Roman Quaedvlieg was on leave due to a separate external investigation.

"The department does not comment or confirm whether any matter is, or is not, under investigation," a spokesperson said on Thursday.

"The department has a robust integrity regime which has been the subject of numerous public statements, including on our website. The secretary has also addressed this issue in opening statements at Senate Estimates."

Mr Quaedvlieg has been commissioner since the Australian Border Force begun operations in 2015.

Acting Immigration Minister Michael Keenan in a brief statement earlier this week confirmed the commissioner was on leave while "a matter" was considered by the appropriate authorities.

The minister did not elaborate on the specifics of the case.