iPhone 5S and iPhone 5C may have limited supply for its sale tomorrow, according to several sources.

AllThingsD's Ina Fried warned that consumers may be disappointed on tomorrow's sale of Apple's new smartphones as supply may be limited. This seconded reports from BGR and 9to5Mac.

Analysts said that one of the possible reasons of the limited supply is that the cheaper iPhone 5C may sell more compared to its full-fledged counterpart. Another possible reason for the short supply is the constraints in the supply chain such as difficulty in building parts of the iPhone 5S.

However, Apple has neither affirmed nor denied any of the aforementioned rumours.

It can be recalled that Apple finally introduced its line-up of smartphones, iPhone 5S and iPhone 5C, last week. The premium smartphone, the iPhone 5S, included most of the iPhone 5 specs and features as well as the much faster 64-bit A7 processor chip, M7 motion-sensing chip and biometrics sensor on the home button of the handset.

Meanwhile, the low-cost iPhone 5C boasts the same, old 4-inch retina display, dual-core A6 chip processor and 8 MP rear camera of the iPhone 5. However, the cheaper smartphone, which is housed in a cheap, plastic casing, offers colour options in blue, green, yellow, white and red.

Consumers can purchase the iPhone 5S for $199 for 16 GB, $299 for 32 GB and $399 for 64 GB with the usual 2-year contract; and the iPhone 5C for $99 for the 16 GB variant and $199 for the 32 GB with the same 24-month lock-in period.

Pre-orders of the iPhone 5S and 5C started last Sept. 13. The new devices will be on sale tomorrow, Sept. 20.