Investors in embattled Tasmanian whisky distillery Nant have been told more than 700 barrels sold to them "have never been filled with whisky".

Key points: Nant won several international awards for its whisky in 2015

Nant won several international awards for its whisky in 2015 2016 investors sold two barrels of whisky for $25,000, with a promised 9.55 per cent return

2016 investors sold two barrels of whisky for $25,000, with a promised 9.55 per cent return Australian Whisky Holdings says over 700 barrels were "never filled"

The whisky's production was financed by investors who bought a barrel of whisky, which would then be bought back by the distillery for bottling after the spirit matured.

According to Nant's website, 2016 investors were offered two 225-litre barrels of whisky for $25,000 — with a guaranteed 9.55 per cent return.

When it matured around four years later, the distillery said it would buy it back from the investor for $36,000.

A letter from ASX listed company Australian Whisky Holdings — which recently purchased the distillery estate — also informed whisky investors "there are many more than this number still unfilled".

Australian Whisky Holdings said it had recently finalised the sale of the Nant Estate in Tasmania's central highlands, becoming "the registered proprietor".

As part of the sale, Australian Whisky conducted its due diligence, which included — according to the company — "the most extensive audit of whisky stock that has ever been done in the history of whisky distilling in Australia".

Australian Whisky CEO Chris Malcolm wrote to investors who purchased Nant whisky barrels from the former owner to inform them an audit of the distillery found "serious anomalies".

"There are a large quantity of barrels which have been decanted, bottled and the proceeds sold however the barrel investors have not been informed or paid," the letter said.

"There is a large number of barrels that are filled with approximately 45 per cent ABV [alcohol by volume] alcohol, new-make whisky, whereas the industry standard is usually 63.4 per cent.

Do you know more about this story? Email investigations@abc.net.au

"There was a significant quantity of barrels that had the owners' names and barrel numbers sanded off the barrels (we do not understand the reason for this)."

Australian Whisky told investors the sale of the Nant Estate in Bothwell was finalised in February, but a deal to buy the Nant distillery business fell through.

Investor feels lucky to have got paid

Peter Bignall, who in 2009 was employed to restore the mill at Nant distillery, said he was paid for some of his work with a barrel of whisky.

After trying to redeem the barrel and move it to his own distillery, he was eventually paid out.

Mr Bignall worries the dispute may affect other Tasmanian whisky makers from attracting investors.

"Anybody who wants to try to raise funds in the future, it'll be a bit harder for them after this," he said.

Mr Bignall worries that the scandal may affect other Tasmanian whisky makers from attracting investors. ( ABC News: Lucy Shannon )

The Nant Distillery is connected to the family of businessman Keith Batt, who in December 2016 filed for bankruptcy, owing millions on a separate failed business.

Australian Whisky told the ABC that while many whisky investors will be paid out, investors who own the non-existent barrels will have to pursue Nant Distillery for their money.

Nant whisky was founded more than a decade ago by Mr Batt, and became an international sensation, winning two medals in the World Spirit Awards in 2015.

A basic 500ml bottle sold for $150.

Last week, the Nant Distilling Company Facebook page posted a letter to investors.

In it, the company said they terminated the deal with Australian Whisky Holdings amid concerns the company would not prioritise Nant investors.

"The Nant arrangement we entered with you, may not be as equal importance to AWH and the relationship they may have with you," the letter said.

"It is our intention to recommence the redemption of barrels and our bottling and dispatch operations."

Attempts by the ABC to contact Mr Batt, and the Nant group of companies were unsuccessful, and emails have not been returned.