An Australian supermarket chain has decided to sell baby formula from behind a counter to protect customers with a "genuine need" for it.

The decision by Coles in some stores follows years of controversy in Australia about shoppers who buy the product only to sell it overseas, particularly to families in China.

Australian parents have complained about a shortage of formula.

Coles is one of the nation's two biggest supermarket chains.

Australian milk formula has been nicknamed "white gold" in China because it is perceived to be safer and of better quality than locally produced products.

It has led to a lucrative practice where shoppers in Australia, known as daigou, buy products and ship them overseas.

According to Sydney's Daily Telegraph, tins of formula bought for about A$30 (£17; $23) in Australia have been resold for approximately A$100 in China.

'Complete nightmare'
One mother from Sydney, Jyoti, told the BBC that purchasing formula for her twins had become "a complete nightmare".

"There have been times when I had to go to five or six shops in the one trip to find any, because there was just an empty shelf or just unsuitable formula left over," she said.

It was particularly hard for parents who need a single type of milk or a specialty formula, she added.

"Parents are just trying to feed their babies in Australia, but other people are buying it up and exporting it," she said.

In recent years, many Australian parents have shared similar frustrations - particularly on social media - and called for greater protections from supermarkets and producers.

One formula maker, Bellamy's, apologised in 2015 for a shortage, which it attributed to "on-selling to overseas markets".

Customers have also posted videos and pictures on Coles' Facebook account, showing other shoppers appearing to defy purchase limit rules by buying tins in bulk.

New rules
The measures mean that infant formula will be sold from behind service desks, or tagged with electronic surveillance lids, at some stores in New South Wales, Coles said.

The supermarket chain and its chief rival, Woolworths, had already limited sales to two tins per customer.

"Coles is committed to ensuring that our customers with a genuine need for infant formula have access to this product," a Coles spokeswoman said in a statement.