SEOUL, South Korea — Embattled Samsung Group Chairman Lee Kun-hee said today he was stepping down from his post at the top of South Korea's biggest conglomerate following his indictment on tax evasion charges.

"I today have decided to resign from the post of chairman of Samsung Group," Lee told a news conference less than one week after he was indicted following a special independent counsel investigation into the conglomerate's operations.

"We, including myself, have caused troubles to the nation with the special probe," Lee said. "I deeply apologize for that, and I'll take full responsibility for everything, both legally and morally."

After Lee spoke, Vice Chairman Lee Hak-soo, considered the chairman's closest confidante, also announced his resignation as well as that of Lee Jae-yong, the chairman's son and heir who is an executive at Samsung Electronics Co.

Lee, the vice chairman, said Lee Soo-bin, chairman of Samsung Life Insurance, would represent Samsung Group externally. It was not immediately clear if the post of group chairman would remain vacant or eventually be filled.

Special prosecutors Thursday indicted Lee on charges of evading 112.8 billion won ($113 million) in taxes, ending a three-month probe in the family-run conglomerate prompted by allegations of wrongdoing by a former Samsung lawyer.

Prosecutors, however, dismissed the most explosive claim — that Samsung used affiliates to raise a slush fund to bribe influential South Koreans — for lack of evidence.

They also decided to indict Lee without arrest, saying his apprehension was too big a risk for South Korea, citing "the extremely competitive global economic situation."

Samsung Group, founded 70 years ago by Lee's father, has interests in dozens of businesses including electronics, shipbuilding and construction. Its companies account for up to 20 percent of South Korea's exports, by some estimates.

Samsung Electronics, its flagship corporation, is a world leader in computer chips, flat-screen TVs and mobile phones. Lee, widely seen as the driving force behind the rise of Samsung Electronics into a global technology force, hinted earlier this month that he might resign over the scandal following questioning by the special prosecutors.

Besides Lee, nine other Samsung executives were indicted.