The Xbox 360 Call of Duty: Modern Warfare 2 limited edition console. Microsoft's ban of Xbox Live members coincided with the relase of the game. ((Dan Steinberg/Associated Press))

EBay says a flood of modified Xbox 360 video game consoles that have been banned from connecting to Xbox Live has hit the online auction site, and is warning users to be wary of what they buy.

"If you are looking to buy an Xbox 360 on eBay in the near future, ask the seller if it has been banned from Xbox Live and be sure to pay by PayPal in case they lie," the company said on its website. "If you do get a banned console, start a PayPal claim."

PayPal is eBay's online payment system, which can reverse charges in the case of fraudulent sales.

The announcement comes after Microsoft this week banned up to one million consoles from accessing its Xbox Live service, where users can play online games with each other or purchase downloadable content such as movies and television shows.

The company enacted the ban on consoles that have been modified by users to play pirated copies of games.

"All consumers should know that piracy is illegal and that modifying their Xbox 360 console violates the Xbox Live terms of use, will void their warranty and result in a ban from Xbox Live," Microsoft said in a statement.

Affected gamers can still get online by signing in from an unmodified machine, but the "modded" consoles are permanently banned from Xbox Live, Microsoft said.

The company has more than 20 million members on Xbox Live.

The ban coincided with the launch of Activision's Call of Duty: Modern Warfare 2, which is on its way to becoming the best-selling game of all time. Video game blogs have speculated that Activision pressured Microsoft into the ban as pirated versions of the game became available days before its Tuesday release.

Call of Duty titles are among the most popular online multiplayer games.