upon the emergence of the Internal Electricity Market (IEM) in the European Union, the leaders of the four above-mentioned regional organisations recognised the need for an EU-wide harmonisation of network access and conditions for usage, especially for cross-border electricity trade. In 1999, ETSO was created as an association with ATSOI, UKTSOA, NORDEL and UCTE as founding association members. However, on 29 June 2001 ETSO became an International Association with direct membership of 32 independent TSO companies from the 15 countries of the European Union plus Norway and Switzerland. At the end of 2001 ETSO membership was enlarged to Slovenia and CENTREL countries as full and associate members respectively. In June 2003 the Czech Republic has been admitted as full member of ETSO.