The white iPhone 4 has been delayed because manufacturers cannot make the phone white enough for Apple, according to reports.

Reports have appeared in Chinese newspaper 21st Century Business Herald that touchscreen glass manufacturer Lens Technology, is facing difficulties manufacturing the white iPhone 4.

A Engadget report claims a worker from Lens' quality control department has allegedly admitted that the company's screen-printing workshop is dealing with some issues with the white iPhone 4 covers.

Apparently the factory's still working out the perfect combination of paint thickness and opacity to achieve the share of white that Apple wants.

Another reason for the delay is said to be that the factory cannot meet Apple's demand for the white iPhones, because they can only manufacture three iPhone 4 glass covers per hour, according to Apple Insider.

Apple Insider notes that the Chinese report claims that each machine owned by Lens Technology can only cut three iPhone 4 glass covers per hour. This means the company's can only meet half of Apple's demand for the iPhone 4.

Although Apple 's launch of the iPhone 4 was plagued with the antenna issues, the iPhone 4 is still in high demand.

The white iPhone 4 is due to be released at the end of July.