A number of bottle shops in Darwin have voted to ease their voluntary restrictions on the sale of cask wine, prompting criticism from police and Aboriginal health workers and a backtrack by one of the major supermarket giants.

Key points: Some Darwin bottle shops have dropped restrictions that limited cask wine sales to one a day, between noon and 7:00pm

Some Darwin bottle shops have dropped restrictions that limited cask wine sales to one a day, between noon and 7:00pm Outlets say the restrictions are no longer needed because of new policies, but police oppose the change

Outlets say the restrictions are no longer needed because of new policies, but police oppose the change Supermarket giant Coles lifted then reinstated the restrictions, Woolworths has made no change

The manager of a bottle shop in Darwin's northern suburbs said cask sales had dropped almost 90 per cent in three years and that a suite of other alcohol restrictions imposed by the Northern Territory Labor Government had made the voluntary measures superfluous.

But police warned that easing the rules would result in more alcohol-related harm, and Coles has now backflipped and agreed to reinstate its restrictions.

High-volume cask wine products have long been considered a major contributor to the staggering rates of alcohol-related harm in the NT, which has the highest rate of per capita alcohol consumption in Australia.

An alcohol review found 44 per cent of Territorians drank at risky levels, compared with 26 per cent of people nationally.

The Territory has limits on alcohol sales imposed by the Northern Territory Government as well as voluntary restrictions introduced by bottle shops.

Two years ago bottle shops in Darwin's northern suburbs, which had formed a local liquor accord, agreed to voluntarily limit the number of two-litre casks one person could buy between noon and 7:00pm each day.

But two months ago, the northern suburbs liquor accord voted to drop the voluntary cask wine restrictions.

Bottle shop manager and chairman of the accord Russell Reid said cask sales at his drive-through outlet in Casuarina had dried up and the restrictions were no longer needed.

He said an average of 500 casks sold in a three-month period last year had dropped to about 80 over the same period this year.

Cask wine prices have at least doubled since the floor price took effect. ( ABC News: Jacqueline Breen )

"I've seen an 86 per cent reduction in cask wines over the past three years," Mr Reid said.

There is no official data to confirm the drop in cask wine sales.

A Government spokesman said there were anecdotal reports of a shift away from cask wine, but said official consumption figures would not be available until later in the year.

Wholesale figures show cask wine sales have been declining for nearly a decade.

Mr Reid said he was "very confident" it was the Government's suite of alcohol policies that had driven the drop and said removing the restrictions was about making the voluntary accord "more efficient".

Since winning office in 2016, the NT Labor Government has introduced a range of alcohol policy changes, including a banned drinker register that restricts who is allowed to buy takeaway grog, as well as a minimum floor price on alcohol.

The minimum floor price has raised the price of cheap alcohol across the Territory.

For example, a two-litre cask wine that was selling for $30 in Darwin this week was available from an interstate retailer for $10.

"Just in the past 12 months, since the introduction of the minimum floor price, 63 per cent [of the decline] has happened in that period," Mr Reid said.

Police oppose change, Coles reinstates restrictions

But police, who are also part of the northern suburbs liquor accord, voted against removing the restrictions and warned the change would result in more alcohol-related harm.

Alcohol seized by Darwin police from the Bagot community in May. ( Supplied: NT Police )

The head of the police unit that tackles sly grog said there were already indications that easing the rules would see an increase in the black market trade of cask wine purchased legally but then onsold.

"Any lifting of restrictions around the sale of alcohol only serves to increase the levels of alcohol-related harm in the community," Acting Superintendent Crispin Gargan said.

"Early anecdotal evidence would suggest there has already been a surge in seizures of cask wine in restricted areas by the Alcohol Policing Division across the Darwin region".

After the restrictions were removed in May, the police unit that targets secondary alcohol supply raided the Darwin Aboriginal town camp of Bagot, where alcohol is restricted, and seized 54 litres including a number of casks.

The change was "very disappointing" to Rodger Williams, deputy CEO of Aboriginal health service Danila Dilba, who said the restrictions should remain in place until the suite of harm reduction measures had been evaluated.

Supermarket giant Woolworths, which is hoping to secure approval in Darwin for what would be one of its largest Dan Murphy's outlets in the country, said its BWS outlets in the city's northern suburbs would be keeping the voluntary restrictions in place.

Coles initially agreed to relax the rules at its Liquorland outlets in the northern suburbs but had since reversed that decision.

"Liquorland regularly reviews voluntary responsible service strategies and is in discussions with NT Police regarding ongoing measures in these stores," a spokeswoman said.

'Nothing has changed', alcohol help groups say

Given different alcohol restrictions apply to different areas in the Northern Territory, it is difficult to know if the reduction in cask wine sales in the northern suburbs has had any impact on alcohol-related harm.

Service providers and welfare groups that spoke to the ABC did not have up-to-date data on alcohol consumption patterns, but said there had been no drop in demand for help.

A man drinks Coke and mouthwash in Darwin. ( ABC News: Jacqueline Breen )

Bottle shop manager Mr Reid said the members of the accord would be "monitoring" the effect of relaxing their restrictions, although he did not provide details of how this would be measured.

He said had seen no decrease in "anti-social behaviour" despite the drop in cask sales, and said he believed alcohol addicts had switched to different products.

"There's no doubt that anti-social behaviour still exists related to alcohol," he said.

"But the problem has shifted to other alcohol products, such as hard spirits.

"That's been very evident, the product shift — we'll just have to keep an eye on that but the issue doesn't seem to be cask wine anymore."

There has also been concern about drinkers shifting to inedible products such as mouthwash and vanilla essence. NT Police will soon have the power to confiscate and tip out those substances when they find them.

Among a handful of people drinking in corners of the CBD who spoke to the ABC, one man who did not give his name was drinking Coke mixed with mouthwash in the early afternoon.

"People [who drink] will get it, whatever they have to do, whatever they have to pay for it," he said.

The Alice Springs-based People's Alcohol Action Coalition was sceptical about the efficacy of voluntary sales restrictions proposed by bottle shops and had campaigned instead for a minimum price.