Why desperate parents are sending pleading letters to Woolworths about their babies.

Baby formula supply remains a serious issue for many parents, and a group is claiming Woolworths’ latest move has made it even harder for them to feed their children.

Sydney father Ivan Chan and two other customers wrote a letter to the supermarket giant – which they later posted on Woolworths’ Facebook page – asking for it to reverse a recent decision.

In August, Woolworths relaxed its strict infant formula limit from two tins per customer to up to eight tins per customer.

Chan and fellow parents said this change has made it much harder for them to find and buy the infant formula they need.

“We are a group of concerned customers who are struggling to obtain baby formula for our babies/toddlers, due to some customers buying eight or more tins of formula,” the letter read.

“We have to keep calling stores all over Sydney to feed our children.

“The problem has become acutely worse since Woolworths increased the per customer limit to eight tins per customer.”

Restrictions have been enforced on baby formula purchases since 2015 due to the increase in demand fuelled by shoppers (known as daigou) buying tins in bulk and selling them to parents in China.

Many Chinese parents have not trusted their own country's milk formula since a tragic melamine contamination killed six babies and hospitalised thousands more in 2008.

Chan and his fellow signees have requested Woolworths reduce their limit to two tins per customer "to ensure adequate supply for Australian families".

In a response to Chan's Facebook post, Woolworths said it would consider making a change to the limit.

"We've been working very closely with our suppliers and recently changed our formula tin limit as a result of improving supply in the market," the comment read.

"We will continue to carefully monitor stock availability, supply arrangements and feedback from customers and will adjust the limit again if needed."

Woolworths reiterated the statement when contacted for comment.

Correction: An earlier version of this story said that Coles had an eight-tin limit. Coles, in fact, has a limit of two tins per customer per purchase.