Prime Minister Anthony Albanese has laid out the terms of an inquiry into Scott Morrison's secret self-appointment to administer several ministries during the height of the COVID-19 pandemic.

Former High Court justice Virginia Bell will lead the inquiry, which will examine how the appointments were made and the implications arising from them.

"We need to have a quick and appropriate inquiry, which is not about the politics but how this happened," Mr Albanese said.

The Prime Minister said the inquiry would make recommendations to government on any changes to provide greater transparency and accountability 'to ensure this can never happen again".

Ms Bell will report back to government by November 25.

Attorney-General Mark Dreyfus said the inquiry was necessary for democracy.

"This inquiry is one which absolutely was made necessary by the solicitor-general's advice, which expressed in the clearest possible terms that what occurred here with Mr Morrison having himself appointed to five ministries was contrary to, inconsistent with, the conventions and practices of responsible government," Mr Dreyfus said.

"This is sinister stuff. This is secret government. This is one of the most appalling things I've ever heard in our federal government."

Mr Albanese said the government chose not to launch a royal commission, which would compel Mr Morrison to appear to give evidence, saying it would be "extraordinary" for the former prime minister to refuse a former justice.

"If it was the case that Virginia Bell felt like she was not getting the cooperation that was required, then I'm certain that other measures could be considered," he said.

Mr Morrison said last week he would participate in any "genuine" process to learn lessons from the pandemic.

His colleagues have warned an inquiry into his secret power grab should not become a witch hunt.

Mr Albanese said it could not be dismissed.

"These are extraordinary circumstances. You can't just dismiss it in the way that [Liberal leader] Peter Dutton has," he said.