A special prosecutor cleared South Korean President-elect Lee Myung-bak of financial fraud allegations Thursday, allowing him to take office next week with his mandate untarnished.

The announcement ended a probe over suspicions that Lee colluded in a 2001 stock case, a controversy that plagued Lee throughout last year's campaign.

"It is fortunate that all suspicions were cleared once again," Lee said in comments released by his office. "I thank the people who have given me trust and support so far. I think the way to repay this is to work harder and devote myself to serving the people and saving the nation's economy."

Government prosecutors had already cleared Lee of the allegations, which he also strongly denied, weeks before the election. But rival lawmakers pushed for the special probe in an apparent attempt to keep the scandal alive through the vote.

South Korean voters, however, overlooked the alleged wrongdoing to give Lee a landslide victory in the Dec. 19 vote.

"The president-elect was not involved in the stock price manipulation," special prosecutor Chung Ho-young said in a televised announcement of the outcome of a 38-day investigation.

Lee's relatives and former business partners had attempted to stop the probe by filing a petition with the Constitutional Court, but the court ruled last month that the investigation could go on, making Lee the first South Korean president-elect to undergo a criminal inquiry. Special prosecutors questioned Lee on Sunday.

Even if Lee had been found at fault, he would have still been able to assume office Monday as scheduled because the constitution grants sitting presidents immunity from criminal prosecution except with especially serious charges such as treason.

However, such a case would have significantly undermined his mandate to assume the highest office in South Korea.

He also cleared Lee of allegations that he had owned a tract of land in Seoul under another person's name and lied about it, and that he gave illicit business favors to a company while serving as Seoul's mayor from 2002-2006.

The scandal came to a head in November with the extradition from the United States of fugitive Korean-American fund manager Kim Kyung-jun, who once had joined Lee in setting up an Internet financial firm.

Kim was accused of making millions of dollars by rigging stock prices from a separate investment company and fleeing to the United States with the ill-gotten gains.

At issue has been allegations by Lee's liberal rivals that the money used for the stock manipulation came from a third investment firm, known as BBK, and that Lee was its real owner — meaning he was involved in the crime.

Lee has claimed the accusations were a plot by the rival party to discredit him.

Just days before the election, a 2000 video surfaced of Lee bragging in a speech that he founded BBK. Lee said the comments were taken out of context.