UP TO ONE million Australians are expected to be forced on to the dole queue in the first six months of the coronavirus crisis, according to government estimates.

Senior Social Services Department officials revealed the stunning estimate yesterday at a Senate inquiry into COVID-19.

Officials warned the estimate had not been revised since mid-March before the full extent of the government's response became clear however the explosion in unemployment since then had been "broadly in line" with expectations.

A detailed breakdown of the weekly spike in jobseekers since late February showed total unemployment applications jumped by more than 500,000 from 815,000 to 1.35 million.

The department has maintained its estimate that unemployment applications will reach 1.7 million by September when the extraordinary coronavirus dole payments are scheduled to expire.

A further 3.3 million workers are estimated to work for companies that have applied for the $1500 a fortnight JobKeeper wage subsidy.

Department secretary Kathryn Campbell said estimating future unemployment was difficult because "none of us have seen this before".

Ms Campbell also revealed officials were working on proposals for Jobseeker payments after the COVID supplements expired but would not confirm if they were considering a permanent increase.

The inquiry also heard that Government Services Minister Stuart Robert was never advised that the MyGov website had been hacked when it spectacularly crashed on March 22 as hundreds of thousands of newly unemployed people tried to log on.

Mr Robert originally blamed a cyber attack for the crash but later corrected the record in parliament.

Services Australia chief executive Rebecca Skinner said officials were operating in "an environment where denial of service attacks may have been expected" and had advised Mr Robert the alarms had gone off.

Asked if the minister was advised "categorically" that there had been a hacking attempt on the website, Ms Skinner said: "Not categorically and he corrected himself in the House".

Ms Skinner said officials knew there would be unprecedented demand for MyGov on March 22 and had increased its capability but building the system to "cope with that one day" would not have been a good investment.

She said MyGov could now handle 90,000 log-ins an hour, up from 6000 before the coronavirus.

Originally published as Just how big our dole queue is going to get