possible to remotely add WP users?

Is there a possibility to remotely add WP users and add them to WPMU Membership levels and thus giving them access to protected pages?
In the documentation I can't find anything about this. Is there an API available that can be called through e.g. POST requests that provide the necessary data (email, name, level) to create users and associate them with a membership level?

Best regards,
Marian