CANBERRA, Aug. 29 (Xinhua) -- One of the Australian government's leading advisers has warned that its drought relief efforts are "condemned to failure."

Peter Harris, chairman of the Productivity Commission, said the government was repeating the mistakes of the past in its drought relief policy.

His warning came as new Prime Minister Scott Morrison was working on a new response to the drought, which has affected 100 percent of New South Wales (NSW), having declared the disaster his top priority.

Harris said farmer subsidies worth 1.8 billion Australian dollars (about 1.3 billion U.S. dollars), announced by Morrison's predecessor Malcolm Turnbull in his final weeks as the premier, had led to higher freight and feed prices.

"If it hasn't worked in the past we are condemned to fail if we keep repeating it," he told Fairfax Media on Tuesday night.

"When you see subsidies being introduced for the cartage of feed around the country, look at the history of what that has induced, higher freight rates and a higher cost of feed."

Turnbull's drought relief package included 500 million Australian dollars (about 366 million U.S. dollars) in low-interest loans for farmers.

Barnaby Joyce, the former deputy PM and Morrison's special drought envoy, dismissed Harris' comments, saying he did not possess a deep understanding of the issue.

"It might be a complete waste of money for Mr Harris with his six-figure job, in his office in the middle of town, but the people who are actually trying to survive don't think it is a joke," Joyce told Fairfax.

Joyce joined Morrison in a tour of farms in south Queensland on Monday where the PM re-committed to drought relief as his "most urgent and pressing need."

Morrison promised that assistance would be available "for as long as the drought goes on."

"It's about drought relief and it's about drought recovery as well," he said.