SAN FRANCISCO: Apple Inc rejoined the EPEAT environmental ratings system on Friday, acknowledging that its decision to stop participating in a program that rates the green credentials of electronic products was a mistake.

The about-face came after reports that various government agencies and schools that use the EPEAT (Electronic Product Environmental Assessment Tool) certification system were considering dropping Apple's products, which include Macintosh computers and iPads.

"We've recently heard from many loyal Apple customers who were disappointed to learn that we had removed our products from the EPEAT rating system. I recognize that this was a mistake," senior vice president of hardware engineering, Bob Mansfield, said in a letter on Apple's website.

Apple has in the past year touted its own green credentials, most recently by announcing an internal initiative to use cleaner energy sources for its data farms in North Carolina.

EPEAT bills itself as a global registry to which consumers can turn for information when shopping for greener electronics. According to EPEAT's website, http://www.epeat.net/, its users include federal and state government agencies, colleges, and several private corporations such as Ford Motor Co and KPMG.

Apple's decision this month to stop participating in the registry would have affected computer-related purchasing decisions by governments and universities because many them are required to use hardware that has been rated by EPEAT.

The city of San Francisco, for example, has a policy that its computers, laptops and monitors must be EPEAT "gold" rated.

Customers reached out to Apple directly, which played a "critical part" in getting Apple back on the registry, said EPEAT Chief Executive Robert Frisbee.

"The scientific community in the U.S. government are big users of Apple," Frisbee said, adding that they were "particularly influential" in convincing Apple to resume its participation.