By Slash Lane

Published: 11:00 AM EST (08:00 AM PST)

Apple has reportedly suspended sales of slide-on cases for the iPhone 4 in its retail stores, as users have apparently experienced issues with scratching and even breaking glass.

An industry source told Cult of Mac that trapped dirt is causing scratches and cracks on Apple's latest handset, which has both a glass front and back. At least a half-dozen case makers are said to be impacted by Apple's ban, despite the fact that they are certified "Made for iPhone."

"Apple is slowly evaluating each and every iPhone 4 case at a secret case testing facility," the report said. "Some may be approved before the holidays. It's literally on a case-by-case basis (pun intended), the source said."

While slide-on cases for the iPhone 4 have apparently been banned, Apple still sells similar-style covers for older iPhone models. The previous-generation iPhone 3GS had a plastic, curved back.

The alleged suspension of case sales is said to have a big impact on manufacturers, many of which rely on availability in Apple's retail stores for sales. Author Leander Kahney also revealed that case makers spend at least $250,000 to create molds.

Last month, one report claimed that Apple was looking into third-party cases that were causing scratches and cracks on the iPhone 4. Ryan Block of gdgt said the iPhone engineering team was in a "quiet lockdown" as it worked to solve the issue, which he dubbed "glassgate."

It was said that slide-on cases could cause damage by trapping material between the phone and the case, eventually scratching, cracking or even fracturing the glass back of the iPhone 4. It was also claimed that Apple had created a lab and new test program to investigate the issue.