Ancient open-air theatres across Greece are crumbling due to neglect and need swift government intervention to rescue them, archaeologists said on Thursday.

Greece, where Classical drama was born in the 5th century BC, boasts scores of theatres that form a key part of the country's classical cultural heritage. But while about 30 are in a state to host cultural events, 76 are in need of urgent repair, they said.

"Ancient theatres need to be constantly preserved, some need to be restored, but what they mostly need is to be used," classical archaeology professor, Petros Themelis told Reuters.

Archaeologists, architects and dignitaries from Greece's political and cultural life have joined forces to push the government to take action to preserve the structures.

"The image of our monuments is discouraging," said former Socialist culture minister Stavros Benos, one of the group's founders. "Our aim is to constructively push the government on this issue."

Greece's renowned Epidaurus theatre, built in the 4th century BC in the northeast of the Peloponnese peninsula, attracts thousands of tourists every year who flock to watch ancient Greek plays by playwrights such as Euripides or Sophocles.

Famous for its acoustics, it is the most used ancient theatre while others have fallen victim to the ravages of time and nature.

The 6th century BC Dionysus theatre on the Athens Acropolis, which served as a model for Epidaurus and where the ancient Greek plays were originally performed, is in disrepair and cannot host cultural events.

Archaeologists said that ancient theatres should be part of every day life in order to be preserved.

"We might restore them, but nature will destroy them again (if they are not used)," Themelis said.

Another 28 ancient theatres are known to exist but have not yet been located or excavated, the archaeologists said.