No part of the ABC will be quarantined from cuts if the national broadcaster's funding shrinks, managing director Mark Scott says.

However, Mr Scott told a Senate estimates hearing on Tuesday that he is confident Prime Minister Tony Abbott will abide by public and private commitments to maintain the ABC's budget.

The Government late last month announced it would conduct an inquiry into the efficiency of the broadcaster's operations, along with that of SBS.

The study will examine the costs of day-to-day operations and propose options to increase efficiency and reduce expense.

Mr Scott told the hearing that if the ABC's funding shrinks, then all of the broadcaster's services will be examined for savings.

"Nothing would be spared from that kind of review, and I can give no guarantee on any services, that any services could be spared, including rural services, if our funding was cut," he said.

"But I'm not expecting that because of the clear commitment that was given to maintain the ABC's funding.

"If our funding were somehow cut, we would need to look at all our services - radio, television, online - in the cities and in the bush."

When quizzed about the level of funding for children's programs in a follow-up question, Mr Scott said they would also be part of a review of spending if funding was cut.

"Senator, if our funding were cut, the ABC board would require us as a management team to look at how best those savings be made," he said.

The Opposition linked the Government's announcement of an efficiency review to recent strong criticism of the ABC's coverage of asylum seekers and intelligence leaks.

"This is not about finding efficiencies, it's about cutting the ABC's budget," Opposition communications spokesman Jason Clare said.

"The Prime Minister gets some bad news and suddenly he starts blaming the media."

However, Communications Minister Malcolm Turnbull says the review is not in response to growing criticism within the Government of the broadcaster.

SBS warns of cut to programs

Meanwhile, SBS managing director Michael Ebeid told the Senate estimates hearing that some foreign-language services may have to be scrapped if the Government cuts its funding.

SBS is concerned the Government's Commission of Audit will target the multicultural broadcaster, which provides radio programs in 74 languages.

"You'd need to have a look at what the size of the funding adjustment would be, but I would find it very difficult to imagine being able to absorbing any material cuts without a change in services," Mr Ebeid said.

He says a merger with the ABC would not save any money.

"The fact is that we are a very efficient organisation and we have been running efficiently for a long time - we've outsourced a lot of our key functions to other external providers who can do things very cheaply - I think there would be very little economic benefit," he said.