Apple is expected to delay the release of the new 5.5-inch iPhone 6 until 2015 due to production problems, an industry analyst said. According to a research note by Ming-Chi Kuo at Taiwanese KGI Securities the 4.7-inch iPhone6 is still making its debut in September, but the larger 5.5-inch model could be delayed.

Kuo said Apple is having trouble with the new in-cell touch panel and its redesigned metal casing.

He said he is concerned that the new scratch-resistant sapphire glass cover that is reportedly fitted into the 5.5-inch model might not "easily pass the drop test near term."

The most conservative scenario is that Apple puts off the 5.5-inch model to 2015, and he expects the 4.7-inch model will come along with the iPhone 5s, and 5c models.

Meanwhile, Hong Kong-based researcher Counterpoint released another report that the monthly sales of the Galaxy S5 of Samsung Electronics fell behind the iPhone 5s in May.