The acceding countries are in midst of an integration and catching-up process, and their equilibrium exchange rates will be subject to gradual changes and shocks over time. Therefore, any premature  2  BIS Review 49/2003  euro area participation has to be avoided.
This corresponds to the economic reasoning behind the Treaty provision that the Commission and the ECB have to examine the achievement of a high degree of sustainable convergence in their convergence reports to the Council before a decision will be taken on any new Member State’s adoption of the euro.