The cuts were detailed by CSIRO chief executive Dr Larry Marshall during a Senate estimates hearing chaired by South Australian Senator Sean Edwards earlier this week.

"It is inevitable going forward that some of those people in support functions will lose their jobs," he said.

"We are working with the NICTA team to establish where the areas of overlap are and as you may imagine, there are a lot of areas of overlap in the support functions so HR, finance, marketing and so on."

The proposed merger, which will see the peak science body's production team merge with NICTA, was announced in February with negotiations now entering the final stage.

"We are very close but as they say the fat lady hasn't sung yet, but we are very close," Dr Marshall said.

"We think of it as a potential merger and I think it's a huge opportunity to bring the two groups ... together and have the one powerhouse of ICT capability in the country."

NICTA's current funding will expire in June 30 leaving close to 600 students and staff without funding in the absence of a merger with the CSIRO.

"If the merger goes ahead then obviously there will be way, way fewer job losses than if it doesn't, because the company will run out of money in the middle of next year," Dr Marshall said

CSIRO's Dave Williams told the hearing the department was doing everything it could to find alternate employment for support service staff at NICTA over the past few months.

"The situation is that over the next 12 month they will lose about 25 per cent of the total budget of the two entities and that could translate in the worst case to more than 200 people," he said.

"We are working on areas of saving costs and we are working on areas of extra revenue to try and reduce that to the lowest possible number."

Dr Williams said the two departments were at a very delicate stage of discussions as the merger was not completed, making it difficult to talk about specifics.

Senior staff had been consulted about the potential staffing modelling with all staff to be consulted once the merger was formally approved.

"We are at a very delicate stage in the discussions because the merger's not complete and NICTA's not part of CSIRO at the moment, so it's a little difficult to talk about specifics," he said.

Dr Marshall said the merger would not impact the studies of more than 300 PhD students currently studying with NCITA.

Under the current merger proposal, a separate company would be established with a chief executive and a board. although it would remain part of the CSIRO for a term.

"At some point in the future we might - and probably would but not for a year or possibly more - actually merge it into CSIRO as we get an understanding of how it operates," Dr Marshall said.