Apple is preparing to produce a record number of its next generation iPhones, expecting strong consumer demand for the devices.

The Wall Street Journal, citing people familiar with the matter, reported that the company is asking its suppliers to manufacture as many as 90 million units of two new iPhone models with 4.7-inch and 5.5-inch displays by 31 December.

It hasn't been clear if the phones would be called iPhone 6S, as is likely given the minimal changes expected, or iPhone 7.

In 2014, the company ordered to produce about 70-80 million of its iPhone 6 and iPhone 6 Plus models.

Apple's upbeat order comes as the company experienced strong sales for the current versions of its iconic iPhones. In the first half of the fiscal year ended in September, the company sold 135.6 million phones, up 43% from the same period a year ago.

Apple is not expected to make significant changes to its next versions, except for adding Force Touch, a technology that can distinguish between a light tap and a deep press, the sources told WSJ. It may also offer a fourth colour for the casing, adding to the available options – silver, gold and space grey.

Despite the minimal changes to the specifications, the company expects consumers to upgrade their handsets to the latest version.

The newspaper said the company has considered adding Taiwan-based Wistron Corp. as its third assembler of new iPhones to meet demand, in addition to existing partners Hon Hai and Pegatron Corp.

Hon Hai, Apple's primary assembler, has been recruiting workers at its main iPhone production base in Zhengzhou, China, anticipating mass production to begin in August, the newspaper reported.

If Wistron is qualified for production, Hon Hai's share of Apple's iPhone orders is likely to be cut. Apple now looks to diversify its assembly partners, in a bid to reduce reliance on a single supplier.