Warren Buffett, chairman of conglomerate Berkshire Hathaway, on Saturday said that railroad BNSF will spend to improve its operations but is not planning to acquire any other businesses.

"At BNSF we will spend a lot of money to have the best railroad possible but we're not going to be buying other businesses," Buffett, 83, said.

Buffett was speaking at Berkshire Hathaway's annual shareholder meeting in Omaha, which draws tens of thousands of people to hear him and partner Charlie Munger answer hours of wide-ranging questions.

He added that Berkshire Hathaway will continue to keep a cash cushion of at least $20 billion.

"We will never be dependent on the kindness of strangers," he said.