In a recent international survey Zeri ranked amongst the world's top 10 experts on Italian art. But, for all that, he was never given a university chair, and was feared and even hated by his fellow historians in Italy. The feeling was mutual: "He was the opposite of the small-minded, dreary, hide-bound Italian intellectual," recalled his close friend Roberto D'Agostino, with whom Zeri co-wrote the controversial satire Sbucciando Piselli ("Shelling Peas") in 1990. "He held them in utter contempt."
Unlike his fellow Italian art historians, the flamboyant Zeri - who in recent years took to appearing on television clad in flowing kaftans as a statement of the gulf separating him from the rest of the art-history world - had no fear of attacking sacred cows.
In the last few years, with the restorer Bruno Zanardi, Zeri questioned whether Giotto had had any significant role in frescoing the Basilica in Assisi, attributing the bulk of the work to Giotti's Roman contemporary Pietro Cavallini. In a memorable and long- running battle with the whole art establishment in 1988 he argued that the Ludovisi throne - the centrepiece of Rome's collection of ancient artefacts and today proudly on display in the newly restored Palazzo Altemps - was a clumsy 19th-century copy of the fifth-century-BC original. And, incurring the wrath of collectors and dealers, he recently unmasked a slough of fake Modigliani sculptures.
Zeri was born in Rome in 1921 and educated at Rome University, where he studied under such famous art historians as Pietro Toesca and Roberto Longhi. He began his working life in the Cultural Heritage Ministry, but his time there was stormy, and his talents soon led him to branch out into lecturing, writing, and organising exhibitions from his base at the treasure-filled home he had built outside Rome in the early 1960s.
In his own, irascible, inimitable way, Zeri repeatedly attacked what he saw as gross incompetence amongst the directors of the Cultural Heritage Ministry, and its envoys in the provinces. After a six-year stint on the ministry's Fine Arts Committee, he stormed out in 1952, loudly denouncing devastating inefficiency and red tape.
In articles for La Stampa, Zeri returned over and over again to the theme of the mismanagement of Italy's cultural heritage, railing against "the ghastly bourgeoisie which controls the country but doesn't deserve to". His criticism was very specific, very trenchant, and made it clear that Zeri believed that non-Italians were better candidates for looking after the country's treasures.
"Copies?" Zeri once said of the reproductions of great Renaissance sculptures removed from the streets of Florence for restoration and never returned. "They should copy the lot and send the originals abroad." But, even abroad, Zeri did not find it was all plain sailing.
A respected lecturer at universities around Europe, and at Harvard and Columbia in the United States, as well as a trustee of museums the world over, Zeri was the only Italian to be nominated a member of France's Academie des Beaux Arts in April 1997. But he fell out with the directors of the Paul Getty Museum in Malibu in 1993 when he tried - in vain - to prevent them from buying a Greek kouros. When they went ahead, he resigned his post as trustee. In the event, the kouros was kept in the cellars for months, and is still surrounded by doubt and controversy over its authenticity.
Zeri leaves the world a mass of writings, though few of the learned articles which the academic world demands of anyone aspiring to join its ranks. Instead, he dedicated his talents to drawing up catalogues for some of the world's greatest collections, for example the four volumes on Italian works at the Metropolitan Museum in New York.
His catalogues of the Spada and Pallavicini galleries in Rome are considered classics of their genre: erudite, impeccably researched but readable at the same time. L'Inchiostro Variopinto (1985) charts his efforts to unmask fakes, while Dietro L'Immagine: conversazioni sull'arte di leggere l'arte (1987; translated into English as Behind the Image: the art of reading paintings in 1990) explores ways of looking at art, and Giorno per Giorno nella Pittura (1994) is a journey through the lesser-known art treasures of the country.
Zeri never limited his studies to the great masters, preferring to delve into minor provincial painters, in order "not to get bogged down in a single specialisation". The former Culture Minister Alberto Ronchey, who in 1994 proposed Zeri as his successor - a proposal not taken up by the government of the time - described Zeri's intellect as immense: "He was not only a critic of Italian art, he worked on a planetary scale. He had a visual memory which was indelible, for everything, even for furnishings."
Zeri's dedication to all aspects of art was inexhaustible. At the time of his death he was art section editor for the Armando Curcio publishing house and, in a belated return to the Cultural Heritage Ministry which he left on such bad terms in the 1950s, Vice-Chairman of the National Council for the Arts.
At the time of his death, Zeri was setting up an exhibition which opens in Turin on 16 November of 16th- to 19th-century landscape paintings of Umbria and the Marches. A few days earlier, he had made a final selection of the 62 works to be displayed. He had also paid a visit to the areas portrayed in the exhibition, areas hit last year by an earthquake which wreaked inestimable damage on the art and architecture.
As his heart gave out, Zeri was planning one of his usual wide-ranging, work-packed weeks: a visit to Milan to oversee the reorganisation of the Palazzo Reale; then to the Quirinale Palace in Rome for the opening of an exhibition of Leonardo da Vinci's Lady with an Ermine; then to Bologna for another appointment.
Federico Zeri, art historian and critic: born Rome 12 August 1921; died Mentana, Italy 4 October 1998.