State prosecutors on Friday raided the offices of KT Corp., the country's top fixed-line operator and No. 2 mobile carrier, as part of their ongoing corruption probe into its chairman.

A team of prosecutors and investigators obtained computer hard drives and confidential documents, including accounting books, from the company's three offices and houses of several executives to corroborate the charges, prosecutors said.

The raid comes just 10 days after the prosecution office first swooped down on the telecommunication giant's headquarters and the residence of Chairman Lee Suk-chae.

In February, a local civic group had filed a dereliction of duty charge against Lee with the Seoul Central District Prosecutors' Office, saying that his business decisions have caused the company huge losses.

The People's Solidarity for Participatory Democracy alleges that the chairman made bad investments in online education and subway network systems, causing the company hundreds of billions of won in losses.

Chairman Lee also allegedly played favorites with unauthorized subcontractors, the civic group claimed. The main complaint is that companies not included in the usual pool of subcontractors working for KT obtained contracts, it added.

Lee also came under public criticism when he left Seoul Saturday to attend an international telecommunications meeting in Africa. It is unusual in South Korea that a high-profile figure is allowed to travel overseas while a criminal investigation is pending. (Yonhap News)