Hellenic Petroleum, Greece’s biggest refiner, said yesterday it plans to hire 297 refinery workers to replace staff that’s retiring. «The Board of Directors has decided to hire 297 employees who will staff new job positions arising due to the upgrade of the refineries and will cover the vacancies arising from retiring staff,» it said in a bourse filing. The company also plans a voluntary exit plan for an undefined number of administrative and research staff. Those workers won’t be replaced, the company clarified. Hellenic Petroleum’s shares fell 1.57 percent on the Athens bourse yesterday to end at 7.50 euros, bringing its market capitalization to 2.29 billion euros. The Athens bourse’s benchmark general index fell 4.62 percent.