CSIRO staff leaders confronted their bosses on Thursday, demanding answers on the fate of more than 1400 ''non-ongoing'' workers at the organisation.

The jobs of about 20 per cent of the Commonwealth science group's 6500 staff were plunged into uncertainty last week after Public Service Minister Eric Abetz imposed a hiring ban on the federal bureaucracy.

The staff freeze threatens to paralyse some of the organisation's premier research projects, with a ban on hiring, extending or renewing contracts effective immediately. Fairfax Media understands the only exceptions are post-doctoral positions and indigenous recruitment.

''It's going to be a huge problem,'' said one staff member, who wanted to remain anonymous.

CSIRO's executive and senior staff have been frantically seeking explanations from government as to how the edict is to be interpreted.