Facebook was thinking about ways to possibly bring children onto its platform long before it launched its first kid-centric app.

In fact, the issue cropped up as early as 2013, when Facebook's Sheryl Sandberg floated potential ways to bring "under 13s" into Facebook, according to newly public documents.

The documents, which were obtained by investigative reporter Duncan Campbell and published by NBC, include thousands of pages of internal messages between high-level Facebook employees over a number of years. Among them is a summary of Sandberg's many meetings with European officials at the Davos World Economic Forum in 2012.

According to the summary provided by Marne Levine, an executive on Facebook's public policy team, Sandberg discussed with one of the European Union's top officials overseeing digital policy how Facebook might reach kids younger than 13 years old.

"We have a great relationship with this European Commissioner," Levine writes of Neelie Kroes, who was at the time the European Commissioner for Digital Agenda. "She and her staff seem open to some kind of Facebook lite service that provides a controlled social environment for under 13s and verifies age and identity."

Here's her full description of the conversation (emphasis added):

We took the time ask her thoughts about under 13s. (Many policymakers in Davos noted that their 10, 11, and 12 year old children are begging for Facebook accounts.) She and her staff seem open to some kind of Facebook lite service that provides a controlled social environment for under 13s and verifies age and identity. (Anthony, her staffer, said that if you ask people whether 6 year olds should be able to play together on the internet, they will say no. But no one objects to two 6 year olds playing together on a safe playground. That's the kind of environment we need to replicate on line. Sheryl's response: "I love you.")

Facebook didn't immediately respond to a request for comment.

While it's not clear if Facebook ever seriously considered such a proposal, it's notable that both Sandberg and Kroes were enthusiastic about the possibility of bringing "under 13s" online. Sandberg was so effusive she responded "I love you" to a staffer's suggestion that 6-year-olds should be able to "to play together on the internet."

Facebook would go on to eventually launch a service aimed specifically at children with Messenger Kids. The app prompted pushback from advocacy groups who said the service could harm young children who aren't yet equipped to navigate social media.

Earlier this year, Facebook disclosed that a "technical error" allowed thousands of children to exchange messages with adults without parental approval — a violation of one of the app's own top safety rules.