Cricket Australia chief Nick Hockley said he was optimistic Wednesday that the five-Test Ashes series against England can be played in front of crowds as scheduled this year, despite coronavirus concerns.

The series is due to start in Brisbane on December 8 before moving to Adelaide, followed by the traditional Boxing Day Test in Melbourne then Sydney and Perth.

While Brisbane, Adelaide and Perth are largely virus-free and fans are allowed into venues, Sydney and Melbourne are both in lockdown battling outbreaks of the Delta variant with case numbers and deaths rising.

Some state borders are also closed, complicating matters.

Hockley told local media rising vaccination rates in Australia and the prospect of "vaccine passports" gave him optimism that the series could go ahead as planned.

"We're hopeful that with vaccination rates increasing that we will be able to complete the series as currently scheduled," he said.

After a glacial roll-out, nationwide vaccination efforts have accelerated in recent weeks with 40 percent of adults now fully jabbed.

Hockley said the pandemic had taught Cricket Australia it needed to be agile in responding to the unexpected, and contingencies were in place.

But he was keen to avoid moving any of the Tests.

"The Ashes is so big, every Test has its own unique character, in the first instance we'll be doing everything we possibly can to play the schedule as planned and very hopeful and optimistic that we will have crowds," he said.

"The one thing I've learnt through this last 18 months is that things can change really, really quickly. We've got a range of protocols that fit any given circumstance and we'll react accordingly. I think it's too early to tell."

Complex and difficult

Whether England bring a full-strength squad remains to be seen, with some players concerned that their families may be unable to join them because of strict Australian border controls, and if they do they may have to live in bio-secure bubbles.

Hockley said he was sympathetic and Cricket Australia was working to facilitate a smooth passage.

"The work we are doing at the moment is to ensure we provide optimum conditions for both sides and all the support staff and families that want to accompany them," he said.

Australia are due to play Afghanistan in a one-off Test in Hobart beginning November 27 ahead of the Ashes, but the Taliban's takeover of the Asian country has created complications in the absence of its commitment to women's sport.

Under the International Cricket Council's regulations, nations with Test status are required to field national men's and women's teams.

Hockley said it was "a complex and difficult situation" and he would take advice from the government in Canberra.

"We are working and in regular contact with the ICC and the Australian government and we will take our lead from them," he told reporters. "As it currently stands the Test is due to proceed."