Apple Inc. has started distributing a software fix for its iPhone smart phone and iPad tablet computer to address potential vulnerability against computer virus attacks, the Japanese unit of the U.S. computer giant said Friday.

Apple Japan Inc. says it has not received any reports about virus infections so far.

A virus-infected unit could allow unauthorized use of voice calls, according to Little eArth Corp., a Tokyo information security firm, adding that personal information may also leak from infected iPhones. Apple Japan also has to fix iPod Nano audio players, some of which get heat up.