Angry investors who purchased barrels of award-winning Nant whisky, only to be left thousands of dollars out of pocket, have been told Tasmania Police will launch a criminal investigation into the saga.

In an email sent to investors on Wednesday, Detective Sergeant JL Ansell from the Fraud and E-Crime Serious Organised Crime Division said police had received "several complaints" regarding "alleged fraudulent conduct".

"A preliminary assessment has been made of the evidence currently available and a determination has been made that a criminal investigation into the allegations will be conducted," the email said.

Almost 900 investors bought barrels of whisky from Nant after production began in 2008, according to a list kept by the business and obtained by the ABC's Background Briefing program.

The barrels, stored in a bonded warehouse on a picturesque estate in the town of Bothwell, north of Hobart, cost as much as $14,000 each.

Nant promised to buy them back once the whisky had matured, with investors to be rewarded with 9.55 per cent compounding interest.

The scheme was designed to raise capital to cover the upfront costs of whisky production and the redevelopment of the estate, which includes a distillery.

But for many investors, the long-awaited payday never materialised.

Investors asked to supply invoices to police

An audit of the business, carried out by the publicly-listed Australian Whisky Holdings after the company announced plans to acquire Nant last October, contained shocking revelations.

The audit revealed more than 700 barrels had never been filled with whisky, an unknown number were missing, and others had been secretly decanted, bottled, and sold to the public without the knowledge of investors.

There are also claims that Nant underpaid employees and contractors. ( Supplied: Facebook )

Pressure has been mounting on Tasmania Police to take action ever since, with detectives inundated by emails and phone calls from investors.

Chris Vlahos, 61, purchased 14 barrels of whisky from Nant for about $170,000. He was later told his barrels did not exist.

"I welcome the investigation — people power will not be ignored," he said.

Nant founder Keith Batt declared himself bankrupt in December 2015, owing $16 million from his previous property ventures.

He consequently removed himself as a director of all Nant businesses, appointing his wife, lawyer, and accountant as replacements.

The Australian Whisky Holdings audit also showed Nant had acquired significant debt, including an Australian Tax Office bill in excess of $1 million.

A number of employees and contractors who worked at the Bothwell estate claim to have been underpaid or never paid at all.

Similar complaints have been made by staff at a number of Nant bars, which have since closed down.

Tasmania Police have asked investors to supply detectives with their barrel ownership certificate, invoices issued by Nant Barrel Holdings Pty Ltd, and any other documentation that may be of use to its investigation.