In a cellular radio system cell identities, in particular E-UTRAN PCIDs, are grouped in accordance with the area (e.g., Tracking Area), to which they belong to in a message transmitted from a radio base station to a mobile station. In one embodiment the grouped cell identity information is transmitted as a broadcast message. A multi RAT (e.g., GERAN/E-UTRAN) capable mobile station receiving such a broadcast message where the IDs are grouped together in tracking area groups is then enabled to determine the neighboring cells that belong to the same area. When cell reselection to an E-UTRAN cell is rejected due to a Tracking Area not being allowed, the mobile station can then be allowed to directly initiate cell reselection to E-UTRAN cells that are not part of the same PCID group, and which do not belong to the same tracking area.