The dispute is about EUR 38 million which Slovenia should pay back to HEP over its delays in power deliveries from the jointly owned nuclear power plant in Krsko, Slovenia.
In 2004, HEP hired a law firm from Washington and a law firm from Zagreb to launch arbitration proceedings before the said centre.
The centre ruled that under the 2001 bilateral agreement between Croatia and Slovenia, the latter was bound to restart with full deliveries of power supplies from the Krsko plant by 30 June 2002 at the latest.
Slovenia delayed in providing power supplies to Croatia nearly ten months, which caused damage to Croatia's HEP.
HEP now expect the relevant judicial institution to decide on compensation to it by the end of this year.
ICSID is considered to be the leading international arbitration institution devoted to investor-State dispute settlement.