The present invention relates to a method and an arrangement for controlling downlink power in a multi-carrier communication network system. The communication network system comprises communication network nodes (15) communicating with a plurality of user equipments (18) on uplink (17) and downlink (16) carriers over a radio interface. Downlink transmit power control commands are sent on at least one uplink control channel to support power control for a multiple of downlink carriers. Each transmit power control command is assigned a pre-determined code word known by said user equipment (18) and said communication network node (15) and/or different pre-determined slot formats, known by said user equipment (18) and said communication network node (15), are used to integrate different number of transmit power control command based on the number of used downlink and uplink carriers.