The "Oracle of Omaha" has revealed that the next CEO of his company will be vice chairman Greg Abel.

"The directors are in agreement that if something were to happen to me tonight, it would be Greg who'd take over tomorrow morning," Mr Buffett said, according to a CNBC report on Monday.

Mr Buffett, 90, has never provided a timetable for his departure.

Succession has been a central issue since 2006 when Mr Buffett, then 75, discussed it in his annual shareholder letter.

Mr Abel, 58, has overseen Berkshire's non-insurance businesses since 2018, after building its Berkshire Hathaway Energy unit into a major US power provider.

Many analysts and investors had viewed the Edmonton, Alberta, native as Buffett's most likely successor, and committed to preserving Berkshire's corporate culture.

Ajit Jain, 69, a vice chairman overseeing Berkshire's insurance businesses, was another CEO candidate, but Mr Buffett told CNBC that Mr Abel's relative youth "Makes a real difference".

Mr Buffett's hand may have been forced after vice chairman Charlie Munger, 97, let slip at Berkshire's May 1 annual meeting, while discussing Berkshire's decentralised business model, that "Greg will keep the culture." He did not mention Mr Jain.

"I suspect Buffett disclosed this reluctantly," though "Abel's coronation is not exactly a surprise," said Jim Shanahan, an analyst at Edward Jones & Co.

Mr Buffett has built Omaha, Nebraska-based Berkshire since 1965 into a $US628 billion empire with dozens of businesses such as Geico auto insurance, the BNSF railroad, Dairy Queen ice cream and See's Candies.

Warren called Mr Abel "a first-class human being" in a 2013 video message.

Mr Abel worked at PricewaterhouseCoopers and energy firm CalEnergy before joining Berkshire Hathaway Energy, then known as MidAmerican Energy, in 1992, which Berkshire took over in 2000.

"There's a lot of smart people in this world, but some of them do some very dumb things," Mr Buffett said. "He's a smart guy who will never do a dumb thing."