Dealing a final blow to Greece's faint hopes of having the ghost of a new Acropolis museum ready in time for the August Olympics, the Council of State yesterday published a decision halting the much-delayed project. The country's highest administrative court ruled that a Culture Ministry decision approving plans for the 94-million-euro building could cause irreversible damage to ancient building remains found on the plot in Makriyianni, under the Acropolis. The antiquities were to have been incorporated in the basement of the new museum - where Greece would like to display the Elgin, or Parthenon, Marbles should Britain give them back - among a network of concrete piers. But in response to a suit by the International Council on Museums and Sites and Makriyianni residents the court accepted that the piers should not be built until a second suit seeking cancellation of the entire project is heard. Though building work is some 20 months behind schedule, the last government claimed the building's shell and a ground-floor hall would be ready in August.