The Board of Inquiry on Thursday confirmed it will deliver an interim report on November 6, the date it was due to hand over its final report to Governor Linda Dessau.

The interim report will contain recommendations for a proposed quarantine program, meaning the state could open up to international flights for the first time since early July.

Premier Daniel Andrews said the government would consider the recommendations and make an announcement "shortly thereafter".

"We need to look at what is in that report but as soon as we can safely have that system set up and have those flights returning, we will," he told reporters on Thursday.

"I am very confident we will be able to have that well before Christmas ... probably toward the end of November."

The final report with a full set of recommendations and findings - such as who made the decision to hire private security and rebuff the Australian Defence Force's help - will be delivered by December 21.

In a statement, the inquiry chaired by retired judge Jennifer Coate said it needed more time to examine additional evidence.

"This unfortunate delay is due to the provision of additional material which occurred after the conclusion of closing submissions on 28 September," the statement said.

"As a result of this additional material, the board has issued several further notices to produce and requests for affidavits. Several documents and affidavits are presently outstanding and may lead to further inquiries."

On October 20, the inquiry called an extraordinary hearing after the Department of Health and Human Services handed over a number of emails it had not originally tendered.

The emails contradicted Victorian chief health officer Brett Sutton's earlier testimony to the inquiry that he did not know private security was guarding quarantine hotels until he became aware of the COVID-19 outbreak at the Rydges on Swanston in late May.

He was asked to provide a new statement within a week.

Mr Andrews was also asked to clarify his evidence to the inquiry after it obtained his phone records and those of his staff.

Victoria's second wave of coronavirus, which resulted in more than 18,000 new infections and 800 deaths, can be traced back to outbreaks at the Rydges and Stamford Plaza hotels.

Health minister Jenny Mikakos and the government's most senior public servant, Department of Premier and Cabinet (DPC) secretary Chris Eccles resigned after the inquiry heard evidence of their involvement in the program.

The DPC annual report for 2019/20, tabled in parliament on Thursday, shows Mr Eccles was paid up to $699,999 a year before he quit.

While flights have been diverted away from the state, the Justice Department has taken over quarantine operations for COVID-positive Victorians who require accommodation while self-isolating.

Opposition Leader Michael O'Brien said he was not concerned about the reporting date delay.

"I'm far more interested in the hotel quarantine inquiry finding us the truth about what went wrong than I am meeting an arbitrary deadline," he told reporters outside parliament on Thursday.

The date had already been pushed back from September 25.

The cost of the inquiry, meanwhile, has almost doubled to just under $6 million.

Australian Associated Press