Apple fans may have to wait longer for the release of iPhone 6 as the handset is currently experiencing some issues in the production line.

Different reports stated different reasons for the delay of the much awaited smartphone. Some claimed that Apple is having difficulties integrating fingerprint sensor to the handset. While others claimed that enlarging the screen size is causing the production delay.

Rumour has it that Apple's iPhone 6 will be powered by A7 quad core processor, which claimed to be faster than the previous processor. The processor will be paired with iOS 7 operating system, which is packed with new and better features.

Apple may have planned to bump the storage capacity of its smartphones. iPhone 6 is said to be coming with 16GB, 32GB, 64GB, 128GB internal storage.

The alleged low cost iPhone, on the other hand, is rumoured to have the specs of either iPhone 4 or iPhone 4S and will be available in a variety of colours. Moreover, the low cost iPhone may feature a cheap plastic casing and not in the traditional aluminium casing like that of the previous iPhones.

However, the Cupertino-based company remained tight-lipped on the rumours surrounding its devices.

Below are the top five reasons of why the release date of iPhone 6 is delayed indefinitely.

Screen Size - Since then, enlarging the screen size posed trouble for Apple. That is why the company took so long to increase the screen size of iPhone. Up to now, Apple is still hesitant in further increasing the screen size of its handset.

Processor - There was a rumour that claimed that Apple recently bought a Taiwanese company to be its own chip maker after it dropped Samsung in making the processors of Apple devices. According to reports, Apple is in the process of buying out United Microelectronics Corporation (UMC), a Taiwanese company listed on the New York Stock Exchange.

Fingerprint Sensor - There was a report that stated problems with the fingerprint-recognition chips could cause a shortage in the number of new iPhones which are available initially.

iPhone 5S Release Date - Rumour has it that Apple will release a low cost iPhone dubbed as iPhone 5S. It is most likely that Apple will release the iPhone 5S until all of the specs, features and hardware of iPhone 6 will be ready.

iPad 5, iPad Mini 2 Launch - Apple is also preoccupied with the imminent release of its tablet line - iPad. iPad 5 and iPad Mini 2 are rumoured to be launched later this year, most probably in September.