Moroccan police have arrested a teenage boy and girl for posting a photograph of them kissing on Facebook, with the incident provoking a slew of copycats, a rights organisation said.

"It involves a teenage boy and his girlfriend. They were arrested on Thursday for violating public decency by posting a photo of them kissing" in the northeastern town of Nador, said Chakib al-Khayari, president of the Rif Association of Human Rights on Friday.

The photograph was taken outside the high school where the two are students.

The young couple are being held in the juvenile detention centre in Nador, where a sit-in has begun to demand their release, Khayari said.

The incident has caused such a stir among young people that a number of other couples have posted similar photos on their Facebook pages.

A local official contacted by AFP confirmed the arrests, but declined to comment.

Khayari said the pair are to appear before a juvenile court judge next Friday.