Facebook’s “nudie police” are out of control — again.

The social network has apologized for taking down a photo of a Renaissance statue of the sea god Neptune after an initial crackdown that cited the artwork’s “explicitly sexual” nature.

Art historian Elisa Barbari had posted a photo of the 16th-Century statue in Bologna, Italy — which shows Neptune naked and holding a trident — to illustrate her page “Stories, curiosities and views of Bologna.”

But Facebook took it down, telling Barbari it violated Facebook’s guidelines on advertising.

“It presents an image with content that is explicitly sexual and which shows to an excessive degree the body, concentrating unnecessarily on body parts,” Facebook told Barbari, according to a screenshot posted by Barbari on her page.

Even more prudishly, Facebook declared that “the use of images or video of nude bodies or plunging necklines is not allowed, even if the use is for artistic or educational reasons.”

Barbari responded defiantly: “Yes to Neptune, no to censorship.”

She later posted an image with the statue in a dress, noting that in the 1950s, schoolchildren used to cover up Neptune.

“Maybe Facebook would prefer the statue to be dressed again,” Barbari wrote.

Facebook has since apologized for the incident, characterizing it as a mix-up.

“Our team processes millions of advertising images each week, and in some instances we incorrectly prohibit ads. This image does not violate our ad policies. We apologize for the error and have let the advertiser know we are approving their ad,” Facebook said.

Last year, Facebook Chief Executive Mark Zuckerberg took heat after the company censored a 1972 Pulitzer-winning photograph from the Vietnam War, which showed naked children running from a napalm attack.

Facebook later reinstated it after recognizing “the history and global importance” of the image.

Facebook says in its community standards guidelines that it restricts nude images “because some audiences within our global community may be sensitive to this type of content”.

Facebook says it removes photos of people displaying genitals or buttocks and some images of female breasts if they include the nipple.

“We always allow photos of women actively engaged in breastfeeding or showing breasts with post-mastectomy scarring,” according to the guidelines.

Nevertheless, in October, the site blocked a breast-cancer awareness ad in Sweden, forcing a Swedish cancer organization to illustrate breasts as squares instead of circles.