Apple's iPhone 5 launch in Seoul will boost the expansion of long-term evolution (LTE) subscribers in South Korea as seen in the massive preorders for the LTE-based smartphone, a global credit rating agency said Thursday.

"The launch of iPhone 5 in Korea, which officially begins tomorrow, is credit positive for KT and SK Telecom because it provides the companies with an opportunity to boost their LTE subscriber base and average revenue per user (APRU)," Serena Won, an analyst at Moody's in Hong Kong, said in a report.

According to SK Telecom, the country's No.1 mobile operator, the 50,000 units that it had allotted for online preorders were sold out last Saturday, while KT said the number of customers who placed preorders surged to 200,000 last Sunday.

The two major wireless carriers began last Friday accepting preorders for iPhone 5 that supports 4G wireless services, or LTE technology. The arrival of the iPhone 5 will give both KT and SK Telecom a distinct advantage over the third mobile operator LG Uplus, whose LTE service has successfully lured customers from KT and SK Telecom, said Won.

According to the telecom operators, there were around 3.4 million iPhone users in Seoul as of October 2012, accounting for around 11 percent of the country's 31.4 million smartphone users. A large number of smartphone users have not yet switched to LTE platforms, thus presenting an attractive opportunity for KT and SK Telecom. Endi