NEW YORK (CNNMoney.com) -- A number of video iPods are infected with a virus, Apple said on its support site Wednesday, and the company was quick to take aim at archrival Microsoft for the problem.

The RavMonE.exe virus, which affects only computers running Microsoft's (up $0.02 to $28.46, Charts) Windows operating system, is on less than 1 percent of video iPods shipped after Sept. 12, Apple said.

Apple's video iPod

It is unknown exactly how many video iPods are affected.

"So far we have seen less than 25 reports concerning this problem," Apple said on its support site. "The iPod nano, iPod shuffle and Mac OS X are not affected, and all Video iPods now shipping are virus free."

Apple has issued instructions on removing the virus - which can be done with free antivirus software - available on its Web site.

In addition to Microsoft programs, Symantec (Charts)'s Norton AntiVirus and McAfee (Charts)'s antivirus software can be used, according to the site.

The iPods were infected with the virus at one of Apple's contract manufacturers.

The virus does not affect Mac customers.

"As you might imagine, we are upset at Windows for not being more hardy against such viruses, and even more upset with ourselves for not catching it," Apple said on its site.

An Apple spokesman declined further comment.

Shares of Apple (up $0.40 to $74.69, Charts) rose modestly Wednesday afternoon.

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