Nintendo has limited the ability for younger Wii U gamers to send friend requests through Miiverse.

The rule affects users aged 12 and under, and was quietly announced in a recent update to the social network.

Nintendo explained it had reached the decision in a bid to protect younger users.

"For the protection of younger users, direct friend requests are not possible in Miiverse for users aged 12 and under," reads a new section of the console's Miiverse Code of Conduct (spotted first by Aussie-Gamer).

Nintendo closely moderates Miiverse posts and removes any offensive text or line drawings.

"At the same time, younger users can make friends on Wii U outside Miiverse by entering each other's Network IDs in the friend list on the HOME menu."

It means that users under 13 can still befriend others, although not exchange messages with them through Miiverse.

"We encourage younger users to make friends on Wii U only if they are friends in real life (such as friends from the same school or neighbourhood). Therefore, do not attempt to exchange your Nintendo Network ID with other users on Miiverse."

Other changes include a five-minute posting limit on Miiverse communities (you'll still be able to comment on existing posts) and stricter notification controls (you'll now only be notified if the original poster responds to your comment, rather than any user).

Eurogamer has asked Nintendo for comment on the changes. We'll update when we hear back.