South Korea's ruling Saenuri Party might call for a probe by an independent counsel into allegations of irregularities in a land deal involving President Lee Myung-bak 's son, local media reported Tuesday.

There is a consensus within the party that the investigation by prosecutors, which cleared those implicated of all charges, was insufficient, reports cited the Saenuri floor spokesman Hong Il- pyo as saying.

The remark came after prosecutors dropped charges against seven people, including Lee's son Si-hyung, who were accused of buying land to build the president's post-retirement residence under the junior Lee's name in breach of domestic law.

The seven were also cleared of accusations they used 1 billion won (852,000 U.S. dollars) in taxpayer money in buying 462 square meters of land in Naegok-dong in affluent southern Seoul.

The prosecution has been criticized for conducting only a cursory investigation into what Lee's critics said was a dodgy land deal aimed at real estate speculation and tax evasion.

Calls for a separate probe by Lee's Saenuri Party are seen as an attempt to distance the party from the conservative leader six months before the presidential election.

The center-left main opposition Democratic United Party is also calling for an independent parliamentary probe and public hearing on the matter.

Lee, who scrapped his plan for a new retirement home, leaves office early next year.