England cricket fans have been warned of the risks of buying tickets for next winter's Ashes series through unauthorised internet auction sites.
Tickets will go on sale to England fans on 19 June
Buyers have flooded the eBay website to sell their tickets at inflated prices after they went on sale this week.
Cricket Australia (CA) said it was monitoring websites and newspaper adverts for any tickets up for re-sale.
CA chief James Sutherland said: "People buying tickets this way risk having them cancelled and losing their money."
Tickets for the five-Test Australia-England series were snapped up at a rate of 10 per second when sales opened on Thursday, with 182,000 bought on the first day.
The hosts have set aside a minimum number of 635,500 tickets for the home members' club called the Australian Cricket Family (ACF), with an overall total of 720,000.
It was intended to give priority to Australian fans ahead of English supporters.
But many were left furious as successful buyers went straight to the internet to re-sell their tickets for quick profit.
One pair for the opening day of the fifth and final Sydney Test attracted one bid of Aus$9,100 (£3,650).
Some Australian fans, who signed up in advance for the ACF system, complained it was English supporters who had hijacked the arrangement and were trying to purchase unauthorised tickets.
But Sutherland added: "Anyone who's bought a ticket under the terms and conditions is not able to sell-on that ticket.
"We are tracking that down. It is a real buyer beware situation."
Sutherland added that English supporters will themselves have good access to tickets when they go on sale to the general public in Australia on 19 June.
"The reality is there will be plenty of tickets for the general public available at most venues," he said.
"And supporters in England can also source tickets through organised tour group operators."