The invention relates to a method for reducing the number of uplink interference peaks during soft handover from a radio base station (RBS A) providing a source cell (12) to a radio base station (RBS B) providing a target cell (13) in a cellular mobile communication system. The invention also relates to radio base station (RBS) and a radio network controller (RNC) specifically designed for carrying out the method. The RNC orders RBS B of the target cell to set up a link to a mobile (MS) involved in the soft handover procedure. Further the RNC orders the mobile to start listening for RBS B of the target cell and to synchronize to RBS B. RBS B synchronizes with the mobile in a downlink (6) but not in the uplink. The invention is characterized in that the RNC orders RBS A to set a RF transmission power floor below which its transmission power must not fall when the mobile receives RBS B in the target cell stronger than RBS A and perceives the signal in the downlink from RBS B too strong. Further the RNC orders RBS A to set said floor active for a predefined period of time.