Managing director David Anderson faced extended questioning from Liberal senator Sarah Henderson over pay and personnel at a fiery Senate estimates hearing on Tuesday.

The senator, who worked at the ABC during the 1990s, said she had witnessed inefficiency and waste at the national broadcaster.

"I don't have any cause to believe that things have improved very much, and there is a lot of concern within the ABC about the inequitable allocation of resources," Senator Henderson said.

She said on one recent occasion the Radio National Drive program had nine producers putting the show to air and Australians deserved to know if some parts of the organisation were impoverished while others were overflowing with staff.

"I don't think there are areas at the ABC that are overflowing with staff," Mr Anderson replied.

The public release of details that would lead to the identification of highly paid staff and reveal their pay packets was an unreasonable invasion of privacy that could expose workers to abuse, the ABC chief told the hearing.

He also said the information was commercially sensitive and would give the broadcaster's competitors an unfair advantage, increasing the ABC's overall costs.

Mr Anderson lodged a formal claim for public interest immunity, saying general information about how much the ABC's 4235 staff were paid was already public.

Senator Henderson said there were no grounds for the move and a similar claim from Australia Post had been rejected.

In a combative hearing that was suspended after the senators attacked each other in raised voices, Mr Anderson was also questioned about social media and outside-work policies.

Senator Henderson claimed a recent speech by Four Corners journalist Louise Milligan at the Women Lawyers Association in the ACT had caused offence and distress.

Mr Anderson said Milligan had permission to make the speech, which was delivered in a personal capacity, and the ABC had not received any complaints about it.

During the hearing, Milligan tweeted a series of responses to Senator Henderson's claims, which she said were false.

Senator Henderson said the tweets were an example of a star reporter "going rogue" and bringing the ABC into disrepute.

But Mr Anderson defended the broadcaster's social media policy, which he said had been updated after a legal payout over previous tweets from Milligan.

The ABC has been allocated an additional $20.9 million in yearly funding over the next four years to reverse the impact of previous budget freezes under the coalition.

Australian Associated Press