John Kerry was pictured on a plane with no mask, and American Airlines said he shouldn't have taken it off

• A passenger photographed John Kerry on an American Airlines flight without a mask.
• The passenger told Fox News he took it off after boarding but wore it for most of the flight.
• Kerry said if he removed it, he only did so briefly, but American said it is "looking into" it.

John Kerry, the former US secretary of state and President Joe Biden's climate envoy, was pictured on an American Airlines flight not wearing a mask.

A photo obtained by The Tennessee Star's Neil W. McCabe shows Kerry sitting and reading on a plane, with a mask hanging from one ear, on a Wednesday flight from Boston to Washington D.C.

Kerry said that if he removed his mask, he did so in a way that was "momentary."

American Airlines said it did not see Kerry without his mask but said that he should not have removed it and is "looking into" the incident.

Fox News confirmed the photo with the passenger who took it. It reported that the passenger, who wanted to remain anonymous, shared a photo of his boarding pass to prove he was on the same flight as Kerry.

The passenger said he took it off shortly before boarding and kept it off for five minutes, but he wore it at the boarding gate and for most of the flight.

Kerry said on Twitter: "Feels like there's some St. Patrick's day 'malarkey' afoot on Twitter."

"Let's be clear: If I dropped my mask to one ear on a flight, it was momentary. I wear my mask because it saves lives and stops the spread. It's what the science tells us to do."

American Airlines says masks can "only can be removed briefly for eating and drinking" and are otherwise mandatory.

The Tennessee Star reported that Kerry "was not eating, nor drinking, even though first-class passengers are often served before take-off," though the newspaper did not say how it had this information.

American Airlines said on Twitter in response to the photo: "Masks are required on board our aircraft, and we are looking into this."

And it told The Independent: "We continue to review the matter and we are reaching out to Secretary Kerry to underscore that all customers are expected to wear masks for the duration of their trip," it said.

The passenger who took the photo told Fox News: "If five minutes is 'momentarily,' he's correct. Not sure being in a plane without a mask for five minutes is excusable."

Biden signed an executive order in January that requires people to wear masks on planes in the US.