The iPhone 6 with a 4.8-inch screen size will attract more customers to upgrade to the new handset, according to the analyst. ADR Studio

As the popularity of bigger smartphones, dubbed phablets, is on the rise, Apple (NASDAQ:AAPL) too is rumored to be working on a bigger iPhone, and if the latest claims of an analyst are to be believed, the 2014 model of the flagship smartphone, unofficially called the iPhone 6, will sport a larger screen.

Peter Misek, an analyst at Jefferies, has predicted, after meeting Apple’s Asian suppliers last week, that next year’s iPhone 6 will be redesigned to incorporate a bigger 4.8-inch screen, compared to the 4-inch screen featured in the existing iPhone 5s.

According to a report from CNET, Misek did not reveal any reasons behind his prediction about the next iPhone iteration's screen size except to say that a bigger screen would attract more customers to upgrade to the new model.

"We think the 85M iPhones eligible for an upgrade when the iPhone 6 launches (we think Apple is targeting Sep 2014) could be boosted by another 5-10M from people who skipped the 5S/5C cycle," Misek wrote in a note to investors.

In the last quarter, around 50 percent of smartphones shipped worldwide had a screen size bigger than 4 inches. During the same period last year, only 20 percent of the smartphones shipped had bigger screens, CNET reported.

Reports about a bigger iPhone 6 have been around for quite some time now even though predictions about the actual size of the phone's screen seem to fluctuate a bit.

Korea’s ETNews also reported last week that the iPhone 6 in 2014 could sport a bigger screen of up to five inches. The report also said that the iPad also would come with a bigger screen of 12.9 inches in 2014.

A Wall Street Journal report recently said that Apple was testing iPhones with screen sizes ranging from 4.8 inches to 6 inches, while KGI Securities analyst Ming-Chi-Kuo predicted that the iPhone 6 in 2014 would feature a screen size between 4.4 inches and 5 inches.

Reuters reported, in June, that the iPhone iteration in 2014 may come with at least two bigger screen sizes -- 4.7-inches and 5.7-inches -- as Apple is considering expanding its flagship smartphone range.

Analysts also believe that Apple needs to diversify its iPhone line-up as the company’s handset is at risk of losing more market share to its competitors, especially to main rival, Samsung (KRX:005935).

“Apple’s first priority should be a premium-tier phablet with a 5-inch screen because that is where the largest new revenue pool is located,” Neil Mawston, executive director at Strategy Analytics, recently told TechCrunch.