The Families Commission and the ministries of women's and Pacific Island affairs appear safe from reforms as the Government focuses on big savings from larger departments.

A planned shake-up of state services will see some agencies merged, but Prime Minister John Key said the spotlight was on sharing backroom services to maximise savings.

He confirmed Dominion Post reports that mergers in internal affairs, agriculture and forestry, and research science and technology were being considered.

But he revealed there were no figures on how many jobs might be lost, or how much money could be saved – despite the Cabinet expecting to sign off the reforms as early as next Monday.

Mr Key said the Cabinet's business committee – a powerful group of senior ministers – was meeting last night for the first discussions on the proposals.

He would not prejudge what cuts were likely, but indicated small departments and agencies were safe as they would not deliver the savings and efficiencies being sought.

There were no plans to axe the Women's Affairs Ministry – which National has pledged in the past to abolish.

"What I'm focusing my attention on and what I want ministers to focus on is where real gains can be made that deliver ... much greater efficiency at a lower cost. The truth of the Ministry of Women's Affairs is it costs very little, and it doesn't involve very many people.

"It's not on a list that I've seen."

Pacific Island Affairs was also not in the spotlight and National had no plans to scrap its promise to UnitedFuture leader Peter Dunne to keep the Families Commission.

Instead, the Government appears to be eyeing big reforms in larger ministries to maximise savings and efficiencies. The Government is also looking at a new state sector productivity commission to get better value out of departments.

Mr Key compared the plans with the overhaul of the health sector last year. That resulted in a decision to pool district health board tasks such as payroll and procurement, costing 500 jobs and saving $700m over five years.

"That's an example where, over a period of time, we think there's hundreds of millions of dollars worth of savings. That's where ministers are focused [in the wider public sector], other than these very small, symbolic ... entities."

The proposals include rolling the National Library and National Archives, and possibly Land Information and Statistics into Internal Affairs and bringing the Food Safety Authority back into MAF. The Foundation of Research, Science and Labour state services spokesman Grant Robertson said it was "bizarre" the Government was so far progressed in planning the changes, but had no costings on savings or estimates of job losses.

"These are significant reorganisations for the departments involved, and I would have thought that in a responsible policy-making approach, you would know that information now."

The time for deciding the cuts was too short, and should be extended to allow appropriate consultation with the departments and agencies involved and the people who used their services.