South Korean President Lee Myung-bak offered a public apology Tuesday for a series of corruption scandals implicating his brother and former aides, an embarrassment for the administration he once called "morally perfect."

"It is all my fault," the somber-faced Lee said in a brief, nationally televised speech. "I will readily accept any criticism. "

The public mea culpa came as his elder brother Lee Sang-deuk and a handful of his former aides are facing an array of corruption charges.

The imprisonment of the elder Lee, who is suspected of taking some 600 million won (529,200 U.S. dollars) from local savings banks, was the last straw for the president as he trudges towards the end of his five-year term.

Some of his key confidants, including former top communications regulator Choi See-joong and former vice knowledge economy minister Park Young-joon, are also behind the bars.

Critics say the scandals are an ironic juxtaposition to Lee's national drive for a "fair society" and claims that he is leading a "morally perfect" administration.

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.

His single five-year term ends early next year, with the presidential poll slated for December. Lee is constitutionally barred from seeking re-election.