Queensland's Human Rights Commission has stepped in after Brisbane City Council banned a group of climate activists from using public library meeting rooms, with both sides forced into mediation.

It's understood the council and a representative of Extinction Rebellion subgroup Grey Power must undertake compulsory conciliation in December, after an activist made a formal complaint to the commission.

The Extinction Rebellion subgroup Grey Power meet in a Brisbane library meeting room in October despite a ban on bookings made by the group. Credit:Lucy Stone

Lord mayor Adrian Schrinner announced the ban, passed by the council to stop climate activists from pre-booking public library spaces, in October.

Cr Schrinner said at the time it was not appropriate for ratepayer-funded public spaces to be used by activist groups planning or encouraging illegal activities.