Sydney - Australian officials Thursday defended its purchase of a 910-square-kilometre cotton farm so the 20 billion litres of water it uses can be returned to the draught-stricken Murray-Darling basin that the nation relies on for its food and fibre production.

Toorale Station, only slightly smaller than Hong Kong, was bought at auction for 24 million Australian dollars (19 million US dollars) from its British owners.

"Returning this water to the Darling will begin to turn around the long-term decline of this once great river," Climate Change Minister Penny Wong said.

But she warned that the gains - water equivalent to 20,000 Olympic swimming pools - would not reach the Murray-Darling estuary near Adelaide.

"Purchases upstream will in these current dry conditions find it difficult to make their way in substantial amounts to the lower lakes," she said. "In other words, this demonstrates the difficulties we face in the Murray-Darling Basin."

Toorale, at the confluence of the Darling and Warrego rivers, will become a national park.

Not everyone is happy: farmers in the region decry the move as bad for the sector and bad for rural jobs. John Cobb, the opposition water security spokesman in Parliament, said turning the Bourke region property into a park was a bad idea.

"I think it's an anti-rural or anti-rural Australia act to buy some of the best, most productive country in western New South Wales, and simply turn it into a park," Cobb said. "That's simply a sop to the New South Wales green movement and the New South Wales Government who are on a land grab." (dpa)