Apple's exclusive iPhone partner in South Korea has reported more than 130,000 iPhone 4 pre-orders in the first 13 hours of registration.

KT Corp  started taking pre-orders on Wednesday online and in its 2,900 shops nationwide from 6am, despite no firm date for the iPhone 4 launch, other than sometime in September.

"We will make utmost efforts for the launch and delivery of the new model," Pyo Hyun-myung, president of the mobile business group at KT, said on Twitter.

According to the Korea Herald, KT had to expand its server as the company’s pre-ordering website crashed due to the number of people wishing to pre-order.

KT is South Korea's number two mobile phone carrier behind rival SK Telecom, who this summer has heavily promoted Samsung's Galaxy S smartphone  powered by Google's Android OS.

Apple iPhone 4