The Acropolis Museum is now just months away from entering service in Greece's struggle with its most implacable cultural adversary.

Its priceless treasures lie in marble halls, hidden from view in giant removal boxes.

A mock-up of the Parthenon sculptures, bathed in clear, natural Aegean light, stares out towards the Parthenon temple itself, 500 metres away.

This may be just a building, but it is also a weapon in a polite, but bitter psychological war.

The battle is between this, the new state-of-the-art Acropolis Museum, and the British Museum in London.

The prize? Greece's holy grail - the Parthenon or Elgin Marbles, removed from the temple atop Athens' sacred Acropolis hill in the early 19th century and transported to Britain, where they have remained ever since.

A key purpose of the €130m (£101m) Acropolis Museum is to reunite the surviving sculptures that once adorned the Parthenon.

The British Museum holds 75 metres of the original 160 metres of the frieze that ran round the inner core of the building.

It also possesses 15 of the 92 metopes - fight scenes in stone which decorated the outer walls - and 17 figures from the groups in the triangular pediments at each end.

Most of the rest of what survives is in Athens; the remainder is scattered in museums across Europe.

"I think it is reasonable to ask for all these pieces to be reunited," says Dr Dimitrios Pandermalis, the mastermind of the New Acropolis Museum project, as he shows off the glass-walled centrepiece gallery, which has been constructed to mimic the dimensions of the Parthenon Temple, 500m (547yds) away.

The central core is surrounded by the same number of pillars as the Parthenon had columns.

Running around the 160m (175yds) long perimeter is a 'dress rehearsal' of the frieze made from plaster casts.

The Ancient Greeks placed the originals high up in the temple and in the shade, but in the museum they will be at eye level.

When the museum opens between September and December this year, the original pieces held in Athens will be in place next to copies of the 'missing' sections.

Marbles campaign

"The moral pressure exerted by the New Acropolis Museum is already at work," says Professor Anthony Snodgrass, chairman of the British Committee for the Reunification of the Parthenon Marbles, which is campaigning to persuade the British Museum to return the sculptures to Athens.

"The effect of the pressure will not be immediate but more cumulative," says Prof Snodgrass, "as the millions of visitors mount up, and then return to their home country (sometimes the UK), the whole world will come to see exactly what the consequences of the British Museum's attitude are."

Prof Pandermalis agrees. "It is clear that for the visitor, one piece is here in the original, next piece in London, the other piece in Athens, next piece in London and some pieces they are half in Athens, half in London, same piece, same figure. So it is a problem."

The Acropolis Museum is expected to attract approximately two million visitors a year.

The British Museum argues that in London, three times as many people are able to view the Parthenon Marbles as part of a collection that embraces all world history.

Greek diplomatic sources say negotiations between Athens and London have stalled and that no progress is being made, despite a suggestion that the top floor of the Acropolis Museum could be given to the British Museum as its Athens annex.

"We will continue the talks on the basis of a cultural exchange or something very good for both museums," says Prof Pandermalis, "and I think finally, it is possible [that they will be reunited]."

Behind his modest academic air Prof Pandermalis hides a steely determination to get results, no matter how bitter the controversy.

The Greeks believe that by constructing the museum with its controlled environment they have neutralized the main barrier to the Marbles' return, which was Athens' corrosive air pollution.

"For the first time, we create an environment, architecturally correct, to present these pieces," says Prof Pandermalis.

But the intention that the sculptures' future will be in the museum and not in their original position on the Parthenon has its critics.

"They are taking all the sculptures away from the rock [of the Acropolis], which is really very sad," says one architect and conservationist.

"I would say clean the atmosphere. If the marbles of the Parthenon cannot take the atmosphere, then human beings cannot take it, and the sculptures should be used to protect us."

He declined to be identified because he works for the influential Greek Ministry of Culture.

Asked whether he was damaging the Parthenon to make the museum better, Prof Pandermalis replied, "No we are not damaging the Parthenon. We will put copies of these pieces on the original building."

Prof Pandermalis is also one of the prime movers behind a proposal to remove two listed buildings from Dionysiou Areopagitou, a beautiful tree-lined pedestrian street that separates the Acropolis from the new museum.

One is a rare 1930's specimen of Greek art deco architecture, and its neighbour is a neo-classical house owned by Vangelis, who composed the score for the Oscar-winning film, "Chariots of Fire."

"It's a problem of the optical view of the environment," says Dr Pandermalis.

Move the buildings

He continues: "These houses, they prevent the visitor from seeing behind them the Dionysos Theatre, the most ancient theatre in the world.

"We don't say we have to demolish these buildings. We have to move these buildings; this is possible."

The anonymous architect greets that suggestion with derision.

"They can't be moved. It will only show the horror of the museum from the street," he says. "From the outside it looks like a factory. It's almost a non building."

The architect is not alone.

Greece's equivalent of the National Trust, Elliniki Etairea, has been campaigning vigorously to protect the art deco and neo-classical buildings.

It points out that Greece undermines its case for the restitution of the Marbles if it is prepared to destroy other elements of its historical heritage.

Critics of the museum were also concerned that it would destroy archaeological treasures beneath its foundations.

But the designers have incorporated an excavation into the fabric of the new museum.

The dig uncovered ruins of Ancient Athens, dating from the Classical period of the fourth century BC to the Byzantine period of the seventh century AD.

The remains are visible beneath glass floors and will be accessible through a series of walkways.

For Professor Pandermalis the museum - approaching completion after years of toil and controversy - is a source of great satisfaction.