Woolworths has increased the price of one of its popular subscription delivery services, with experts urging Australians to pay attention to what they put in their shopping baskets. 

Delivery Unlimited will rise from $15 per month to $17, while the annual subscription will increase from $119 to $149. 

The change, brought in this week, is the first time in over five years that the supermarket giant has lifted the subscription cost.

Under the service, subscribers do not pay delivery fees for same-day or next-day Woolworths orders of $75 or more. 

However, this excludes the Delivery Now feature, which sees groceries reach customers' doors in as little as 60 minutes. 

A spokesperson for Woolworths said the supermarket chain is changing the Delivery Unlimited fee to cover an increase in the service offerings. 

‘We are continuing to roll out thousands more delivery and pick-up windows throughout the week across the country to give customers even more convenience when it comes to their weekly shop,’ they said in a statement. 

'To ensure we can continue to deliver a fast, reliable and highly convenient online shopping experience for customers, we are adjusting our Delivery Unlimited subscription rates.'

It is the second time in six months that a vital Woolworths service has seen a price hike.

The supermarket group announced a new $2 surcharge for all click-and-collect and home delivery orders placed on Sundays and public holidays, starting in February. 

The fee was necessary to cover the higher cost of picking and packing orders on those days, the chain said.

Financial comparison site Canstar has previously urged Australians to 'pay attention' at the grocery store when it comes to price rises.

Supermarket pricing will face increased scrutiny from July 1 under new regulations by the federal government banning large retailers from charging excessive prices. 

There are significant penalties for non-compliance. 

'The majority of Australians have changed how they shop in a bid to save money, showing how the climbing cost of living has turned a weekly chore into a strategic exercise,' Canstar spokesperson Eden Radford said in May.

'Households are spending real time and mental energy trying to stretch their dollar at the supermarket, and Canstar's research shows they're getting increasingly savvy about it.

'Switching to home-brand products is one of the simplest ways to take back control of your grocery bill. 

'A family of four could save over $2,400 a year just by swapping half their basket, and with many of those products winning Canstar Customer Satisfaction Awards, they don't have to sacrifice quality to do it.

'The new price gouging laws coming into effect in July are a step in the right direction, but they certainly won't replace the need for consumers to stay informed and shop smart.'