Two influential investor advisory groups sharply rebuked Bank of America Corp Chief Executive Kenneth Lewis over his handling of the buyout of ailing Merrill Lynch & Co, recommending he be stripped of his role of chairman at the bank's upcoming annual meeting.

The reports from RiskMetrics Group Inc and Glass Lewis & Co on Friday add to pressure on the 40-year Bank of America veteran, who faces widespread investor anger over the bank's stock slide and government bailouts since announcing plans to buy Merrill last September.

Many investors complain the bank did not thoroughly study Merrill's finances before agreeing to buy it in a shotgun merger, after less than 48 hours of talks last September. They say the bank also failed to disclose details on Merrill's losses in last year's fourth quarter ahead of a shareholder vote on the deal, which closed January 1.

Both advisory groups, whose recommendations are key for many large investors when casting corporate ballots, recommended that shareholders oppose Lewis' re-election as a director -- and so as board chairman -- as well as the reappointment of lead outside director O. Temple Sloan and the election of several other board candidates.

They also supported a shareholder proposal to split the chairman and CEO roles among different people, a measure proponents say would make the board more independent.

While shareholders are not voting on whether to remove Lewis as CEO, Glass Lewis urged them to question whether Mr. Lewis is the right leader for the company's future.

Bank of America, the largest U.S. bank by assets, said the recommendations were disappointing and it continues to discuss our reasoning with large shareholders.

Bank spokesman Scott Silvestri also said the company believes it has acted legally and appropriately in our disclosures around the Merrill Lynch acquisition, and that the acquisition will ultimately create value for Bank of America shareholders.

The bank's annual meeting is set for April 29 in its hometown of Charlotte, North Carolina.

Bank of America in January got a government bailout, including $20 billion in new capital, to help it absorb Merrill. The funds came after Merrill lost almost $16 billion in the last quarter of 2008.

Bank of America overall has received $45 billion in taxpayer money since October.

Activist investors have called for heads to roll on the board. In its report, RiskMetrics said an absence of board leadership failed to curb Lewis' penchant for empire-building.

The Change to Win Investment Group, which advises a coalition of union pension funds and has campaigned to oust several Bank of America directors, including Lewis, said it welcomed the advisers' recommendations.

The responsibility for effecting this critical and overdue leadership change now rests with shareholders, including the large mutual funds and investment managers whose votes will be decisive, said Bill Patterson, the group's executive director.

In addition to Lewis and Sloan, RiskMetrics also opposed the re-election of board members Jackie Ward, Frank Bramble, Monica Lozano and Robert Tillman, citing poor oversight of management, while Glass Lewis said it opposed the election of three former Merrill Lynch directors to the board.

A day earlier, another shareholder advisor, Proxy Governance Inc, recommended that shareholders vote to split the CEO and chairman roles and opposed the re-election of Sloan and another director, Thomas Ryan. It did not advise shareholders to vote against Lewis' re-election to the board.

(Additional reporting by Jonathan Stempel)

(Reporting by Martha Graybow, editing by Matthew Lewis and Gerald E. McCormick)