Australia's leading scientists are concerned that the CSIRO will lose millions of dollars in international grants.

Reports this week say some of our top minds have been warned by international colleagues that CSIRO funding is too uncertain.

Retired CSIRO fellow Dr Nick Abel says the United Nations Development Program had directly raised concerns with one of his former colleagues.

“The UN told him that in their view, the new CEO was not reliable,” Dr Abel has told ABC reporters.

“And they were frightened that if they did hand over a lot of money to CSIRO under contract, there was a danger that he might cancel those contracts and leave them with the ultimate embarrassment for the UN, which is millions of dollars of unspent money.”

The uncertainty is linked to changes being implemented under new CSIRO boss Larry Marshall.

While billions of dollars were pledged for climate research after the Paris climate talks last year, the CSIRO has since embarked on a new innovation and industry focus.

Dr Abel says it has led to a “dramatic reduction” in “public good” science.

He said great things often came from seemingly unrelated origins, like the biological control of rabbits through Myxomatosis, and Calicivirus.

“They were hugely economically beneficial. And the Government paid for it, CSIRO did it. No company's going to do that,” he said.

“What company would get into the virology research that's going to produce that kind of benefit because they can't capture the revenue from the farmers because the thing spreads?

“It is a plague and spreads like one and kills the rabbits and no company can say: ‘Hey, we did it. We've come to collect your payment for it’.”

Dr Abel unleashed on the move away from science for the public good.

“I've become convinced in the absence of any financial arguments within CSIRO, economic arguments in relation to Australia, social arguments in relation to our nation, that it is ideologically driven,” he said.

“A 100-year-old organisation that was the national pride of Australia is turning into a national embarrassment.”

CSIRO CEO Larry Marshall sent an email to staff in February in which he described climate science as “proven”.

“That question has been answered, and the new question is what we do about it, and how can we find solutions for the climate we will be living with,” he said.

Former CSIRO research manager Dr Peter Craig has retired from the organisation, and so is no longer gagged by any employment agreement.

He was outraged by Mr Marshall’s excuse for going backwards on Paris deals.

“[It's] a transparently false reason for stopping climate science. Somebody compared it with cancer research,” he said.

“We know what cancer is, we can stop cancer research. It makes no sense whatsoever.

“The COP21 [Paris] agreement actually requires an increase in climate science, not a decrease in climate science.

“Within months of the agreement being reached in Paris, Australia is reneging on the agreement.”