(12)The ECB has recourse to the national central banks to carry out ESCB tasks to the extent deemed possible and appropriate. In the case of each SIPS, the relevant Eurosystem central bank is designated as the competent authority for assessing the compliance of that SIPS with the oversight requirements under this Regulation. In the case of a SIPS of pan-European importance, the oversight is carried out by the ECB as the designated competent authority. However, in the case of such a SIPS, where there is a proven, long-standing oversight relationship between it and a national central bank over the previous five years, two Eurosystem central banks, i.e. the national central bank with which the long-standing oversight relationship has been established, and the ECB, are designated as competent authorities.