Outgoing US first lady Melania Trump has caused a stir after removing her mask while meeting young patients at the Children’s National Hospital on Tuesday (Washington time).

Ms Trump’s decision to remove her mask during her fourth annual visit was in breach of written hospital policy, which states: “Everyone must wear a mask at all times while in any Children’s National facility to prevent the spread of COVID-19.”

An official statement released by the White House on Tuesday defended Ms Trump, explaining that numbers inside the room were limited and that her visit had followed regulations for public speakers, based on health guidelines for the District of Columbia.

“Wearing a mask is not required when a person is giving a speech for broadcast or an audience, provided no one is within [1.8 metres] of the speaker,” the statement said.

It also said Ms Trump remained more than 3.6 metres away from everyone else, while her reading was broadcast to 325 hospital rooms.

A hospital spokesperson told CNN the same thing, echoing advice about regulations in the state, without referring to the hospital’s own policy.

There appeared to be adequate social distancing in place as Ms Trump spoke from a lectern in footage posted to the hospital’s Facebook page.

Unlike her husband, Ms Trump is not a constant user of social media. But she did post some photos of hospital visits to her official FLOTUS account on Tuesday – mask-free, they appeared to be from previous years.

Tweet from @FLOTUS

Ms Trump was wearing a mask when she arrived at the hospital, but removed it before addressing attendees.

“It is wonderful to be here. This is one of my favourite events during the holiday time and I’m very excited and looking forward to reading a book,” she said.

“I’m thinking of you all. Stay strong and well and Merry Christmas and happy holidays.”

Ms Trump then read Oliver the Ornament Meets Marley & Joan and Abbey to the children present, and to those watching the broadcast from their rooms.

-with agencies