A team of special prosecutors are set to indict seven to eight people involved in a purchase of land for President Lee Myung-bak's post-retirement residence, local media reported Tuesday.

Those expected to be indicted reportedly include Lee's 34-year- old son Si-hyung, who last year bought 462 square meters of land in an affluent Seoul neighborhood jointly with the presidential security service to build the president's retirement home.

The land deal sparked public criticism following media revelations that the plot was purchased in Si-hyung's name, a violation of South Korea's real estate law.

In addition to allegations of real estate speculation and tax evasion, the junior Lee is also suspected of misappropriating taxpayers' money by purchasing the land at a below-market price and letting the security service pay more.

Both Si-hyung and Lee's brother Sang-eun were summoned by the prosecutors for questioning, and first lady Kim Yoon-ok was recently asked to submit a written statement on her alleged involvement in the land deal.

The prosecutors, recommended by the main opposition Democratic United Party and begrudgingly appointed by Lee last month, are poised to announce findings of a 30-day probe on Wednesday.

The president on Monday rejected the prosecutors' request for extending the investigation by 15 days, citing its potential influence on the upcoming presidential election.

The scandal has been the latest embarrassment for the president, whose closest aides and elder brother Sang-deuk are jailed for their involvement in a series of corruption scandals.

Before being elected to lead South Korea, Lee himself was mired in a financial scam that implicated his former colleague at an investment company called BBK.

The five-year tenure of Lee, who was pressured to scrap his plan to build his retirement residence, ends early next year. He is constitutionally barred from seeking re-election.