The man, who was not named, was believed to be from south-west Sydney and married with children, according to the Sun Herald.
Australia's Department of Foreign Affairs said it was attempting to verify the reports, but it was "very difficult to do so".
"Due to the extremely dangerous security situation consular assistance is no longer available within Syria or Iraq," a foreign ministry spokesman said in a statement.
The reports came two weeks after Afghan-born Mohammad Ali Baryalei, Australia's most senior IS recruit, was reportedly killed in Syria.
It followed claims that hardline IS chief Abu Bakr al-Baghdadi was killed in US-led airstrikes near the Iraqi city of Mosul on Saturday, although US officials could not confirm if he had been present.
The Australian government passed a law criminalising travel to terror hotspots in October, in response to fears about the flow of foreign fighters to the Middle East.
Some 70 Australians are believed to have already made the journey, with another 100 supporting them with recruitment and funding from home, the government has said.
Fifteen Australians, including two suicide bombers, are already thought to have died fighting in Syria and Iraq, Australia's then intelligence chief David Irvine said in late August.
The country raised its terror threat level in September and carried out extensive counter-terrorism raids in Sydney and Brisbane, with Attorney-General George Brandis warning last week that Australians should brace for more large-scale operations.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
