Michael Voss reports from Athens.

It follows revelations that British Museum staff cleaned the sculptures with damaging copper scrapers and caustic chemicals 60 years ago.

Culture Minister Evangelos Venizelos said a new book by a British expert strengthened Greece's case to win back custody of the classical sculptures, known in Greece as the Parthenon Marbles.

The minister told a news conference: "Britain's position is that they preserve the marbles better than anyone else in the world and they don't need the help of a southern European country".

But describing the cleaning error as "tragic", he said the book by historian William St. Clair "shot down" this argument, "in a resounding and impressive way."

Smith: formal request

The book claims British Museum workmen in 1937-38 removed paint and chisel marks from the sculptures in the mistaken belief that the white marble underneath was the original surface.

The cleaning irreparably damaged the historic patina in places, according to the third edition of "Lord Elgin and the Marbles", published on June 8.

Mr Venizelos said he will send a formal request to British Heritage Secretary Chris Smith proposing the formation of an international committee to evaluate the conditions under which the 2,500 year-old sculptures are kept.

Museum: 'public issue'

The marbles consist of 17 figures and are part of a frieze more than 160m long.

They have been housed in the British Museum since the early 19th century after Lord Elgin, then Britain's ambassador to the Ottoman Empire, removed them from Athens' ancient Parthenon atop the Acropolis.

Britain has refused to return the marbles, saying they were better kept in the British Museum, safe from the notorious smog of the Greek capital and enjoyed by millions of visitors.

The British Museum admits the damage had been caused but played down the fracas which is front page news in Greece.

A spokesperson said: "Staff responsible for the mistreatement were dismissed and disciplined. This was all a public issue at the time."