They may be bedfellows at the heart of Australian public service broadcasting, but the ABC and SBS say getting up close and personal by co-locating isn’t for them.

Both national broadcasters have expressed scepticism of one the key recommendations of the efficiency review recently delivered to the Abbott government – the co-location of ABC and SBS administrative facilities in Sydney and Melbourne.

Senior sources at both networks are reported to have said the idea is unworkable and could not be achieved without additional costs, running into tens of millions of dollars.

As both broadcasters work through their official responses to government over the review’s recommendations, the co-location suggestion has apparently caused the greatest anxiety to SBS, with fears it could be swamped by the ABC, culturally and financially, if they were to share offices.

The ABC and SBS receive around $1.4 billion in funding a year from the government and the review, led by former Seven West Media chief financial officer Peter Lewis, has looked at ways both organisations can work more efficiently and reduce costs.

While the review is confidential, many of its recommendations have become public knowledge in the last month. Its proposals generally suggest that the ABC should adopt a more commercial approach, and for instance, charge users to access special content on its iView online catch-up service.

The review has also suggested the ABC should abandon digital radio and focus on streaming radio programs online, and raise $70 million by selling off its production studios and outsourcing work to the private sector.

The ABC is about to begin developing a $176 million facility in Melbourne’s Southbank, which it has designated as its future television production centre in Victoria. Contradicting this plan, the review has noted that “there may be scope for the ABC to rethink the inclusion of two large TV studios in the Melbourne accommodation project”.

The review also proposes that SBS should be allowed to air more advertisements to increase its revenue. Free-to-air commercial broadcasters, who compete fiercely for advertising revenue, are likely to oppose the idea, along with SBS viewers.

The biggest efficiency saving for the government and the broadcasters is likely to relate to transmission contracts with Broadcast Australia, which costs both broadcasters close to $300m a year.

Last week Finance Minister Mathias Cormann played down the prospect of the review’s recommendations being adopted, saying it was a “report to government, not a report from the government'”.