Treasury Secretary-designate Stephen Mnuchin and his then-fiancee, Louise Linton, arrive on Capitol Hill for Donald Trump’s inauguration on Jan. 20, 2017. (Saul Loeb/Associated Press)

The U.S. Treasury’s Office of Inspector General is reviewing the flight taken by Treasury Secretary Steven Mnuchin and his wife, Louise Linton, last week to Louisville and Fort Knox, Ky., following criticism of their use of a government plane on a trip that involved viewing the solar eclipse.

“We are reviewing the circumstances of the Secretary’s August 21 flight . . . to determine whether all applicable travel, ethics, and appropriation laws and policies were observed,” counsel Rich Delmar wrote in a statement to The Washington Post late Thursday.

“When our review is complete, we will advise the appropriate officials, in accordance with the Inspector General Act and established procedures,” Delmar added.

The trip faced a torrent of criticism last week after Linton posted a photo to Instagram showing her descending from the steps of a government jet while clad in high-fashion designer labels, which she individually named. When one woman questioned her, Linton fired back that the woman had less money than her and was “adorably out of touch.”

[Treasury secretary’s wife boasts of travel on government plane, touts Hermes and Valentino fashion]

Louise Linton, wife of Treasury Secretary Steven Mnuchin, caused controversy on Aug. 21 when she boasted of traveling on a government plane and tagged high-end fashion designers. (Elyse Samuels/The Washington Post)

Treasury officials have defended Mnuchin’s Kentucky visit as “official government travel” worthy of the flight aboard an Air Force jet. The one-day trip included stops at a Louisville chamber luncheon and America’s famous gold stash at Fort Knox, where Mnuchin, Senate Majority Leader Mitch McConnell (R-Ky.) and others viewed the eclipse.

“The Secretary of the Treasury at times needs to use a government aircraft to facilitate his travel schedule and to ensure uninterrupted access to secure communications,” a Treasury spokesperson said this week. “The Department of the Treasury sought and received the appropriate approval from the White House. Secretary Mnuchin has reimbursed the government for the cost of Ms. Linton’s travel in accordance with the long-standing policy regarding private citizens on military aircraft.”

The White House referred comment to the Treasury.

[Ethics group wants to know what led Mnuchin to view eclipse in Kentucky]

Treasury secretaries and other Cabinet members not involved with national security have traditionally flown on government planes only on rare occasions, including international trips, while taking commercial airlines for other domestic travels.

Cabinet officials can request government flights for specific criteria, although Department of Defense policy calls it “a premium mode of travel involving high costs and limited resources” and urges federal employees to make “every effort . . . to minimize travel cost.”

Sen. Ron Wyden (D-Ore.) last week requested a “detailed explanation” of the travel and justification for use of the government aircraft. One watchdog group, the Citizens for Responsibility and Ethics in Washington, also has requested records into the trip, saying it seemed “to have been planned around the solar eclipse.”