The heir of a late duke who sold Sting his Tuscan winery 25 years ago said the singer has hit a flat note with an apology for comments the family deem slanderous.

Sting told the weekly magazine Sette on August 13 that he was persuaded into buying the Palagio winery near Florence in 1997 after tasting an “excellent” glass of red wine offered by the owner, Simone Vincenzo Velluti Zati di San Clemente.

The singer, however, said it later turned out that the wine was a Barolo from Italy’s Piedmont region, and not a local Tuscan Chianti at all.

The magazine labelled the move “a hoax” and claimed the singer “had been tricked” into the purchase.

Sting, in the interview, said he only realised the truth about the wine’s origins after he had purchased the Palagio estate, including its vineyards, and he noticed guests pouring the Palagio red into the bushes rather than drinking it.

He said he and his wife became determined to “avenge” themselves by producing “an excellent wine also from the Palagio vineyards”.

The 45-year-old son of the duke, who died in 2012 aged 86, wrote a long, stinging rebuke to Sting’s accusations, calling them “slander, poisonous and completely false”.

Simone Vincenzo Velluti Zati said it would have been completely out of character for his father to have passed off Barolo for Chianti, and said Sting’s use of the interview and the anecdote to promote a new organic pizzeria on the estate was “in poor taste”.

In his letter, Mr Velluti Zati said Sting’s allegations “not only do not respond to the truth, they are highly damaging to the memory of my father and to my reputation”.

Sting responded with a letter on August 24, which was obtained by the Associated Press (AP), offering his “sincere and unequivocal apologies”, and acknowledging that the story “as reported was disrespectful to the memory of your distinguished father”.

Sting called the duke “an honourable man, who never misled me”, and said the anecdote was instead self-deprecating, highlighting the fact that 25 years ago he was unable “to distinguish a Barolo from a bar of soap”.

Mr Velluti Zati told the AP on Tuesday that the apology was a “necessary act” from the singer that was hardly convincing.

He has not decided yet whether to take any further action.