The Australian media's "right to know" campaign stepped up this week in stark contrast to what was happening in Parliament House's committee rooms.

The Senate estimates process gives the opposition, crossbench and government backbench senators a chance to grill officials - albeit with a minister keeping a close eye - about the finer details of their work.

Opposition senators routinely use it as an opportunity to grandstand, but the hearings do usually elicit some useful information.

Officials are allowed to take questions on notice if they don't have the answers immediately to hand.

In theory that allows them to get back to senators with detailed breakdowns of costings or policy applications.

In practice, it lets them avoid answering tricky questions while the world looks on.

Take Monday's session with the Department of Prime Minister and Cabinet.

Its senior bureaucrats and minister Mathias Cormann took some 125 questions on notice - to be later answered in writing - during nearly seven hours of questioning.

Things they couldn't recall off the top of their heads or find in their binders of details included:

* who was involved in a phone call about the US pulling out of Syria and whether notes were taken;

* who knew what when about a US investigation involving Alexander Downer;

* what Prime Minister Scott Morrison told US President Trump during a phone call (about which there were apparently no notes taken) about the same inquiry;

* whether Australia suggested any guests for Morrison's White House dinner in line with normal practice;

* what, if any, briefings the prime minister was given on the drought while he travelled;

* how Barnaby Joyce reported while he was a special envoy on drought.

Labor frontbencher Penny Wong told colleagues the stonewalling diminished accountability.

Officials also flagged potential harm to the bilateral relationship with Australia if they confirmed reports the FBI interviewed Downer, or whether the prime minister's office sent a list of guests for the White House dinner.

"You've got to be kidding!" Wong said to that last one.

Morrison's week in the US was the culmination of a two-year diplomatic campaign emphasising the length and strength of Australia's ties with America.

But here we were being told a century-long relationship with our strongest ally could be derailed by the revelation of the mere existence of a list of guests.

Of course, the unspoken part was that it wasn't so much whether a list was sent as who was on it.

Morrison has made it abundantly clear he doesn't wish anyone to confirm a Wall Street Journal report the White House knocked back his request for Hillsong pastor Brian Houston to join the dinner.

On the matter of Trump's phone call to Morrison about a politically-charged investigation that has caught up Downer, it quickly became apparent there was no written record of the conversation.

No written record means nothing a freedom of information request can turn up.

Similarly, it wasn't clear whether bureaucrats are given specific directions around preserving messages on apps like WhatsApp and Signal, which are theoretically subject to FOI.

One senior official didn't even know whether his messages to colleagues were automatically deleted.

Labor has seized on the Right to Know campaign to use for its own political ends.

Leader Anthony Albanese told colleagues to link it to "the fact we have a prime minister who refuses to give a straight answer to a simple question".

But it isn't a political campaign.

The Australia's Right to Know coalition of 18 media groups - including AAP - and the union formed in 2007 and has pushed governments of both stripes to make laws fairer.

Media organisations appearing before a press freedom inquiry made the point that the federal government sets the example on secrecy, and its approach trickles down to lower levels of government.

If it's okay for politicians at the top levels to dismiss things they don't want to talk about as gossip or accuse journalists of endangering national security, then local councillors keen to keep things quiet follow suit - and the public loses out.

Australian Associated Press