OMAHA, Neb., May 3 (Reuters) - Warren Buffett on Sunday criticized the government's stress tests of 19 large U.S. banks, saying they ignore strengths in lenders' business models, and said he would buy more shares of three big banks in the portfolio of his Berkshire Hathaway Inc (BRKa.N: Quote, Profile, Research) (BRKb.N: Quote, Profile, Research).

Speaking at a press conference, Buffett said those three banks -- Wells Fargo & Co (WFC.N: Quote, Profile, Research), U.S. Bancorp (USB.N: Quote, Profile, Research) and M&T Bank Corp (MTB.N: Quote, Profile, Research) -- do not need more equity capital, and "we would buy stock in any of the three banks at present prices."

Buffett expressed no opinion on the capital needs of another Berkshire holding, SunTrust Banks Inc (STI.N: Quote, Profile, Research). (Reporting by Jonathan Stempel and Lilla Zuill, editing by Maureen Bavdek)