The decades-long restoration effort on Athens' famed Acropolis is set to speed up with the removal of 17 carved stone squares from the ancient landmark for cleaning, Greece's Culture Ministry says.

Officials from the ministry's Central Archaeological Council (KAS) said that of the 17 squares or metopes, 14 will be from the west side of the Parthenon, which experts say, is in a "lamentable state."

According to an article published in the Athens daily Kathimerini newspaper, another metope, depicting a centauromachy or a fight in which centaurs take part, will be taken down from the south side and two more from the north side of the monument.

Restoration of the pollution-ravaged friezes of the Acropolis first began in the mid-1970s.

The ongoing project has involved painstaking repairs on major monuments on the Acropolis, including the Parthenon, the Erechtheion and Athena Nike temples and the Acropolis Walls.

The architectural masterpieces suffered from both pollution and a flawed reparation attempt in the 1930s, when workers used iron clamps in their repairs that eventually rusted and cracked the marble.

Efforts have gathered momentum in recent years mainly due to the Athens 2004 Olympics and British criticism that Greece has abandoned its ancient treasures to the forces of acid rain and pollution.

Archaeologists last year removed six metopes from the west side of the Parthenon and officials reportedly hesitated about approving the removal of an additional 17 metopes, fearing it would leave the Parthenon bare.

They finally decided to proceed with the removal, saying the work is crucial if the landmark is to be preserved.

Preservation experts have used marble from the ancient quarry on Mount Pendeli, the site just north of Athens where the ancient Greeks originally found the marble used to build the Acropolis monuments.

Culture Ministry officials have said that all secondary work on the ancient monument will be completed by 2020.