May 1 (Reuters) - Warren Buffett’s Berkshire Hathaway Inc on Saturday said first-quarter operating profit rose 20%, and that it extended its recent aggressive stock repurchases by buying back $6.6 billion of its own stock. Operating profit increased to $7.02 billion, from $5.87 billion a year earlier. Berkshire also reported net income of $11.71 billion, or $7,638 per Class A share, compared with a net loss of $49.75 billion, or $30,653 per share, a year earlier. (Reporting by Jonathan Stempel in New York; Editing by Alex Richardson)