Apple said it will replace iPhone Duo handsets that developed screen problems days after the foldable went on sale. BBC News and The Verge reported the company acknowledgment Monday. Photos online showed lines and cracks on the inner display of Apple's first foldable phone.

Apple said it is aware of an issue affecting the inner screen of a small number of units. Owners should contact AppleCare, the company said. The handset carries a high starting price in the UK and US markets. Reports of cracks appeared on Reddit and social media after Friday's general sale.

Experts on the early pages said too few examples were public to judge a broader defect rate. Apple did not post a full technical root cause Monday. The Verge said the company framed the problem as limited, not a full recall.

Foldable phones have faced hinge and crease wear at launch before. Replacement programs are a common first step while engineers dig into the cause. The pages did not list how many units Apple had already swapped.

What we know: Apple will replace a small number of iPhone Duo units with cracked inner screens.
What we don't: The full cause, and how many devices are affected worldwide.