Apple is reported to have placed orders for between 70 million and 80 million of its next-generation iPhone devices, against a backdrop of speculation that the company is set to offer its first device in the family with a large screen.

According to The Wall Street Journal (WSJ), this compares with 50 million to 60 million orders for the iPhone 5s/iPhone 5c launch last year, indicating that Apple sees the introduction of its new devices driving customer demand to higher levels.

Initial deliveries will be focused on an iPhone with a 4.7-inch screen, which will form the replacement for the current iPhone 5s. Shipments of a bigger device will begin in September.

It was suggested that one “possible hiccup” the company is facing is that display makers are struggling with the production of 5.5-inch iPhone screens, which feature touch sensors integrated into the display in order to reduce thickness.

It was also mooted that it will feature a sapphire crystal covering, “a more durable but costly alternative to glass”.

With these new production methods taken into account, WSJ said that Apple has asked component manufacturers to provide additional parts in order to take into account the potential for a higher failure rate.

A recent research note from RBC Capital Partners suggested that a large-screen iPhone would provide Apple with a boost in its home market.

Large screen smartphones, or phablets, are also making up an increasing share of smartphone shipments in Asia, which is becoming an increasingly important region for Apple.