by Sky News
The stark advisory follows a report by a team of engineers who determined this week that a part of the flat-topped rock on which the ancient Parthenon sits, is starting to give way, threatening the stability of the landmark monument, the state news agency ANA reported.
The 2,500-year-old Parthenon, built at the height of Athens' ancient glory, is a marble temple dedicated to the goddess Athena, patron of the city.
It is the most important surviving building of Classical Greece and revered as an enduring symbol of democracy and Western civilization.
News of the Acropolis' decay and the threat it poses to the Parthenon has sent shock waves across the country.
It also underscores how vulnerable the country's national treasures have become throughout four years of brutal budget cuts during Greece's fiscal crisis.
On Wednesday, after an urgent meeting of the Central Archaeological Council, experts determined "instability over quite a wide area", following a landslide in early January.
The boulder "of considerable size" tumbled from the south side, rolling down to the entrance of the most visited site in the Greek capital.
Senior culture ministry officials say they are working to control the decaying side although they have refused to comment on whether urgent funding will be available to prevent any further decay.
"Much of the decay has been caused by drainage pipes stemming from the old Acropolis museum, situated on the rock also," said the culture ministry's Lena Mendoni.
"We have already begun studying the damage to ring fence and repair it," she told local media.
The landmark archaeological site remains open at present with hundreds of tourists daily visiting the monument.