Two of Australia's big supermarket groups Coles and Woolworths said on Friday they've collected more than 4 million AU dollars (3.98 million U.S. dollars) in donations from shoppers to help flood-affected Queensland residents.

The latest figure puts Coles donations at 2.3 million AU dollars (2.29 million U.S. dollars), while Woolworths is fast approaching 2 million AU dollars (1.99 million U.S. dollars).

Woolworths has also pledged to match shopper donations dollar for dollar, which is likely to make it the biggest corporate donor, ahead of the Commonwealth Bank with its offering of 1.35 million AU dollars (1.34 million U.S. dollars).

To date, sports organizations, celebrities and big corporations have all contributed to the Queensland Premier's official flood relief fund, which is currently at 45.5 million AU dollars (45.3 million U.S. dollars).

Volunteering Queensland spokeswoman Vanessa Codling said that at least 20,000 people had registered to help.