South Korean President's son Lee Si-hyung (C) enters the office of the special counsel in Seoul, South Korea, Oct. 25, 2012. South Korean President Lee Myung-bak's only son was summoned Thursday for questioning over allegations of irregularities in a land deal. (Xinhua/Park Jin hee)

South Korean President Lee Myung-bak ' s only son was summoned Thursday for questioning over allegations of irregularities in a land deal. "I will explain everything as it is,"Lee's 34-year-old son Si- hyung told reporters before entering the office of the special counsel re-investigating the case that could potentially implicate the president.

Last year, the junior Lee and the presidential security service jointly bought 462 square meters of land in an affluent neighborhood in southern Seoul to build the president's retirement residence.

The plot of land was purchased in Si-hyung's name, however, a violation of South Korea's real estate law that prompted allegations of real estate speculation and tax evasion.

The junior Lee is also suspected of purchasing the land at a below-market price by letting the security service pay more, which raises suspicion he had misappropriated taxpayers money.

Public criticism over the retirement home scandal prodded Lee to scrap his plan, though prosecutors who initially probed the case acquitted everyone involved in the deal, including Si-hyung.

The case is getting a second look after the president's conservative ruling Saenuri Party and the center-left main opposition Democratic United Party agreed to conduct an independent counsel.

Attorney Lee Kwang-bum, recommended by the opposition Democratic United Party and nominated as the special counsel by the reluctant president earlier this month, can conduct the probe for up to 45 days.

The case marks the first time a child of an incumbent leader has been summoned as a suspect.

It is also the latest embarrassment for Lee, whose closest aides and elder brother Sang-deuk are jailed for their involvements in a range of corruption scandals despite his claims his administration is a "morally perfect" one.

The eldest one of the president's three brothers, Lee Sang-eun, is also expected to be summoned for questioning over transactions of 600 million won (about 544,000 U.S. dollars) in cash he reportedly gave Si-hyung to buy the land.

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.

Lee's five-year terms ends early next year. He is constitutionally barred from seeking re-election.