Customers have complained about a shortage of a popular iced coffee brand in South Australia, with its maker telling the ABC the drought and more demand for milk are to blame.

Key points: Iced coffee varieties have been missing from South Australian supermarket shelves

Iced coffee varieties have been missing from South Australian supermarket shelves Lion Dairy & Drinks says the drought and increased demand are to blame

Lion Dairy & Drinks says the drought and increased demand are to blame Customers have posted their concerns on social media

Two-litre bottles of Farmers Union Iced Coffee have been missing from supermarket shelves in recent days, prompting dozens of people to share their concerns on social media.

Lion Dairy & Drinks, who own the iced coffee brand, said tough conditions had impacted supply.

"Extreme weather conditions — including drought, together with significant cost increases across water, feed and energy — have contributed to the challenges facing dairy production in Australia, which has resulted in lower milk supply and increased milk price," a spokeswoman for the company said.

"At this time we are also experiencing an increase in demand for our dairy products and we were unable to source the additional milk to fulfil this volume.

"Unfortunately, as a result, we have had some intermittent supply shortfalls on some products.

"We apologise for any inconvenience this is causing our customers or consumers."

She said it was doing all it could to "source additional milk" and would continue to communicate and work with customers "to mitigate against shortages".

Online outrage from customers

Several people posted on Farmers Union Iced Coffee's Facebook page complaining about the shortage, alongside pictures of empty supermarket shelves.

Farmers Union Iced Coffee cartons at an Adelaide petrol station. ( ABC News: Eugene Boisvert )

"Okay. So we have been to seven different stores — Foodland, Woolworths, Coles, IGA and Aldi," Mandy McKenzie Robertson wrote.

"No-one has any 2-litre FUIC!!! Some don't even have the smaller cartons.

"Do we need to declare a national emergency? There will be riots! Help!!!"

Daniel Woodlands said he needed "a good scull now".

"I average 2–4 litres a day — at $4 for 2 litres you can't go wrong," he said.

Other brands not impacted

The Lion Dairy & Drinks spokeswoman said 2-litre Farmers Union Iced Coffee bottles would start returning to shelves from Monday.

"All other Farmers Union Iced Coffee sizes remain readily available," she said.

Fleurieu Milk Company sales and marketing manager Clay Sampson said his company was supplying flavoured milk as usual.

"We don't have any issues," he said.

A Dairy Australia spokeswoman said "the combination of elevated costs and relatively steady milk prices has eroded profitability" for dairy farmers.

"This is driving milk production lower in year-on-year terms, as farmers reduce herd sizes, supplementary feeding rates, and in some cases exit the industry," she said.

South Australian dairy farmer Casey Treloar 's tearful farewell attracted more than a million views. ( Supplied )

Earlier this year, South Australian dairy farmer Casey Treloar made headlines with a tearful farewell to her family's dairy farm in Parawa, south of Adelaide.

"The clock has run out and it's time to say goodbye," Ms Treloar said.

"We are getting 38 cents a litre across the year and it's completely unsustainable. We can't really afford to keep going anymore.

"We've come to a point where we can't do it any more — it breaks my heart."

Ms Treloar's farewell struck a chord with Facebook users with the video amassing more than 1.6 million Facebook views.