The supermarket giant recently said it would slash the price of 3500 grocery items, but provided details of just 16 price cuts.

That pledge, and a move by rival Coles to move to national pricing, were attacked as meaningless spin by consumer advocates, who said there was no way of checking whether or not the supermarket giants were as good as their word.

The Woolworths initiative - which follows calls for full transparency from leading consumer advocate Frank Zumbo - shows prices of products for each of its more than 800 stores, with shelf, promotion and unit prices.

However, it does not show if a product has been permanently discounted.

Woolworths director of supermarkets Greg Foran said customers wanted greater transparency, as well as lower shelf prices.

The grocer had been working to overcome "IT obstacles" involved in listing prices.

"This is the first step in that journey and, whilst there is clearly a lot more to be done, it will mean customers have even more access to prices and can make more informed choices about where they shop," Mr Foran said.

Woolworths had developed the site itself "at considerable cost" and took full responsibility for the data, which would be updated at 6am each Monday.

Under the Trade Practices Act it must ensure the prices are correct at time of publication. That requirement was one of the stumbling blocks retailers pointed to before the relaunch of the GroceryChoice website by consumer group Choice was shelved by the federal government last year.

Woolworths would continue to post weekly specials online, as well as sending out eight million catalogues to mailboxes each week, Mr Foran said.