A former Italian soldier regarded as the model for the hero of Captain Corelli's Mandolin - Louis de Bernières's bestselling novel set on the Greek island of Cephalonia during the second world war - has launched a fierce attack on the book as an unacceptable smear against Greek resistance to the Nazis.

In an interview with the Guardian, Captain Amos Pampaloni, 89, a Florentine whose experiences almost exactly reflect those of the fictional Corelli, accuses the British author of rewriting the story of Cephalonia's war and "pandering to racism" by portraying Greek partisans as "barbarians".

Mr Pampaloni's onslaught is likely to fuel controversy about de Bernières's story on the island, where a US-backed film, starring Nicolas Cage as Captain Corelli, is being shot.

Under a barrage of complaints from Cephalonian resistance veterans and politicians the film-makers have given undertakings that the movie will be a straightforward love story and will not repeat de Bernières's most controversial claims.

The author was persuaded to cut inflammatory passages from the Greek edition of his book, which has sold 1.5m copies worldwide, and recently conceded that he "might be wrong" about the communist-led Greek resistance.

But the campaign in Cephalonia against the book appears to be growing, despite the boost to its tourist industry. Last week the Greek government was criticised for providing soldiers and ships for the film's battle scenes.

The novel tells the story of a love affair between the daughter of a Cephalonian doctor and a captain in Mussolini's army of occupation, who helps turn Italian troops against the Germans and survives the subsequent massacre of more than 9,000 of them.

Woven into the drama is an unremittingly hostile account of the role of the Greek resistance, who are portrayed as torturers, rapists and cowards who refuse to fight the Germans. In particular, de Bernières claims the partisans refused to support the Italians in their confrontation with Hitler's troops in September 1943.

Speaking for the first time about the book at his home in Florence, Mr Pampaloni said Cephalonian guerrillas did fight alongside the Italians.

"The picture painted of the Greek partisans is unacceptable," the Italian veteran said. "To speak of the Greeks as barbarians, who killed for the sake of it, is pandering to racism."

Like de Bernières's hero, Mr Pampaloni was a captain in an artillery regiment on Cephalonia and like Corelli, he had an affair with a local girl. Like Corelli, he played a central role in the decision to attack German troops and like Corelli, he was shot and left for dead after the Italian defeat.

But, whereas Corelli returned to Italy to be a fireman, Mr Pampaloni fought for a year with the partisans and helped lead the liberation of Cephalonia in 1944.

In an email to the Guardian Bernières denied that Corelli was inspired by Mr Pampaloni.