South Korean special prosecutors say they've raided the home of the president's eldest brother as part of an investigation into alleged irregularities in funding the president's retirement house.

Opposition lawmakers have accused President Lee Myung-bak's office of selling Lee's son land for the house at below market value. They have also accused his office of using nearly $1 million in state funds for the purchase of the Seoul property.

Special prosecutors say they raided the house of Lee's brother Tuesday and will be opening an investigation into his role in the deal.

The president's office denies ordering any special deal for Lee's family.

Lee ends his single, five-year term early next year. Elections are set for December.

Lee apologized in July over the arrest of another brother on bribery charges.