A mother of four says she was shamed into covering up by National Gallery of Australia staff as she breastfed her baby daughter.

Staff then explained it was a "food and beverage issue" and breastfeeding was not allowed inside the gallery because there was the potential for milk spills.

Christie Rea was told to ''cover-up'' as she breastfed her baby daughter at the National Gallery of Australia.

"It was absolutely humiliating," mother Christie Rea said of the incident.

"Women who breastfeed shouldn't be shamed into sitting away in a back room."