Apple on Friday advised iPhone 3G users in many countries to replace the device's power adapter following reports that metal prongs broke off and stuck in power outlets, creating a risk of electric shock.

Apple said it will exchange the ultra-compact USB adapters for a redesigned model, without charge, in retail stores and online starting Oct. 10.

In the meantime, iPhone 3G users who received the tiny USB adapter with their phone or who bought it separately should immediately stop using it. Apple said iPhone 3G owners should use its standard USB power adapter, which has fold-up prongs, or charge the device by plugging it into a computer.

The recall affects ultra-compact USB power adapters sold in the U.S., Argentina, Canada, Chile, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Japan, Mexico, Panama and Peru.

Adapters with a green dot on the bottom are safe and do not need to be replaced, Apple said.

For more information visit http://www.apple.com/support/usbadapter/exchangeprogram/