South Korean media say prosecutors have raided the offices of the Presidential Security Service, searching for evidence of wrong-doing in the purchase of a retirement home for President Lee Myung-bak.

Yonhap reports that investigators are looking Monday for evidence of alleged irregularities in the purchase of a plot of land on the southern edge of Seoul to build a retirement home for Mr. Lee after he leaves office in January.

The lot was jointly purchased by Mr. Lee's son, Lee Si-hyung, and the Presidential Security Service. Critics say the security service paid too high a price for its share.

Investigators say they will question Mr. Lee's wife, Kim Yoon-ok about her possible involvement in the purchase. The questioning will be done in writing rather summoning the first lady for interrogation.