US imports of Brunello di Montalcino could be blocked, unless officials receive guarantees that the wines have been made using the specified Sangiovese grape variety.

The move follows the seizure by Italian authorities last month of hundreds of thousands of bottles of 2003 Brunello di Montalcino on suspicion that winemakers had used varieties other than Sangiovese in their production.

A letter from the US Treasury's Alcohol and Tobacco Tax and Trade Bureau to the Italian embassy in Washington said US customs authorities had been told to "withhold the release of all shipments" of the premium Tuscan wine from 9 June unless Italy or importers could demonstrate that only Sangiovese grapes had been used.
 
A report from Reuters, which had obtained a copy of the letter, said the decision had been taken after Italy had failed to provide information on the producers, brand names and any other vintage wine implicated by the investigation.
 
"The Brunello di Montalcino case presents an issue of deception of the American consumer," the letter of 7 May reportedly stated. "Once you provide the list of producers and brand names and vintages of the affected products, we can narrow our request (to customs authorities) for the withholding of the release action just to those brands and vintages."
 
Reuters reported that a spokesman for the Alcohol and Tobacco Tax and Trade Bureau had confirmed the contents of the letter and said "nothing has changed" since it was sent.
 
Around 25% of the 6.5m-bottle annual production of Brunello di Montalcino is sold in the US.