Apple is reportedly facing problems with the production of 3-D sensors used for facial recognition in its upcoming iPhone X device, slated for shipping early November.

The facial recognition feature of the new device is used to unlock phones and for users to authenticate payments on their handsets.

However, iPhone X has been plagued by a number of production issues, fircing the company to push its shipment date to Nov. 3, while the other new smartphones - the iPhone 8 and iPhone 8 plus launched earlier this month.

Nikkei Asian Review quotes two executives working for iPhone suppliers as saying that 3-D sensor part makers are still struggling to reach a satisfactory level of output and also improve their yield rate.

It is not sure whether Apple could meet large orders after iPhone X's launch. But it is rumored that the iPhone X was being churned out in small quantities, around some tens of thousands daily.

iPhone X is exclusively assembled by Hon Hai Precision Industry at its factory in the central Chinese city of Zhengzhou.

Besides the fcial recognition feature, the strong point of the iPhone X is its OLED display. Both the iPhone 8 and iPhone 8 plus devices use LCDs like previous Apple handsets.

Demand for iPhone 8 and iPhone 8 Plus appears to be weaker than that of their predecessors, but Apple has not made any official comment on that.