Warren Buffett, the chief executive of Berkshire Hathaway Inc, will testify next week before the U.S. panel examining the causes of the deep financial crisis.

The Financial Crisis Inquiry Commission, a Congressionally appointed panel charged with writing by the end of the year a full account of the crisis, said Buffett will testify with Moody's Corp Chief Executive Raymond McDaniel on June 2 in New York.

The hearing will look at the credibility of credit ratings, and the investment decisions made based on those ratings, the panel said in a release on Wednesday.

Credit rating agencies have been accused of contributing to the global financial crisis by assigning inflated ratings to subprime mortgage-related products.

Buffett earlier this month defended credit rating agencies as an investment, including stakes by Berkshire Hathaway.

He told Berkshire's annual meeting that rating agencies made the same mistake that he, politicians, mortgage brokers and others did in overestimating the health of the housing market.

During the first quarter of this year, Buffett further reduced his stake in Moody's, which stood at about 13 percent as of March 31.

Buffett said at the annual meeting on May 1 that the agencies, which also include McGraw-Hill Cos' Standard & Poor's and Fimalac SA's Fitch Ratings, have scant capital needs and have strong pricing power.

Buffett will be one of the biggest names to appear before the 10-member panel, which is modeled after the Pecora Commission that probed the 1929 Wall Street crash.

In the past few months, the commission has also heard from Goldman Sachs CEO Lloyd Blankfein, JPMorgan CEO Jamie Dimon, former Federal Reserve Chairman Alan Greenspan and former Bear Stearns CEO James Cayne.

It must deliver its findings to Congress and President Barack Obama by December 15.

Also scheduled to testify on June 2 are current and former Moody's executives, including Nicolas Weill, the group managing director for Moody's Investors Service, and Brian Clarkson, former chief operating officer for Moody's Investors Service.

The full list of witnesses can be found at: http://www.fcic.gov/hearings/06-02-2010.php

Credit rating agencies are facing tough reforms in the financial regulation legislation moving through Congress.

The Senate version of the bill would have the government set up a clearinghouse to match rating agencies on a semi-random basis with debt issuers.

That could ease pressures the agencies face to assign rosy ratings to securities issued by the firms that hire them, backers said.

Another provision in the Senate's legislation would require federal regulators to develop their own standards of credit-worthiness rather than rely solely on assessments from rating agencies.

Shares of credit rating agencies dropped when the Senate approved the measures on May 13, but it is unclear whether they will make it into the final bill, which must be melded with a version passed by the U.S. House of Representatives.

(Reporting by Karey Wutkowski; Editing by Tim Dobbyn)