CSIRO has announced it will axe up to 350 jobs across the country as it struggles with long-term financial challenges.

The national science agency owns and operates the Parkes Observatory and Radio Telescope at Alectown in the Parkes Shire.

In a statement announcing the decision on 18 November, CSIRO said it had reached a "critical inflection point", with funding failing to keep pace with the rising costs of running a modern science agency.

It plans to cut between 300 to 350 full-time equivalent positions across its research units - at which facilities and what roles specifically however, is yet to be determined.

It is unknown if staff at the Parkes Observatory will be affected at this stage.

"The exact number of roles impacted and where they are based will not be known until later in the process, following consultation with staff," a spokesperson has told the Parkes Champion Post.

It's the latest in a series of cuts at CSIRO, with more than 800 jobs already lost in the past 18 months, the CSIRO Staff Association said.

The association slammed the decision and said it was a "very sad day for publicly funded science in this country".

CSIRO began engaging with staff days following the announcement.

“These are difficult but necessary changes to safeguard our national science agency so we can continue solving the challenges that matter to Australia and Australians,” CSIRO Chief Executive Dr Doug Hilton said.

CSIRO said an 18-month review of its research portfolio found it needed a sharper focus on areas like clean energy, climate and farming resilience, and advanced technologies to drive the next wave of innovation in core Australian industries.

And that other research activities would "need to be deprioritised", including in areas where the CSIRO lacked the scale to make a significant impact.

“CSIRO’s reason for being is to deliver the greatest possible impact for the nation through our research," Dr Hilton said.

“As today’s stewards of CSIRO, we have a responsibility to make decisions that ensure we can continue to deliver science that improves the lives of all Australians for generations to come."

In its announcement CSIRO also said it would need to invest between $80 and $135 million per annum over the next 10 years into essential infrastructure and technology, including critical repairs and maintenance.