In addition, he said that the rail industry as a whole remains concerned about safety after a recent string of accidents.

"It's true that the world is going to need an improved tank car," the iconic investor said in an interview with Reuters. How to transport oil by rail safety is "all" the industry is thinking about, he said

Among the worries he cited was the potential for cyber attacks at Berkshire companies, particularly those with large physical facilities such as BNSF and utility operations.

"It's something that the CEOs of our companies worry about plenty," he added.

BNSF plans to move into tank car ownership and buy its own fleet of up to 5,000 new crude oil tank cars with safety features that exceed the latest industry standards.

(Reporting by Luciana Lopez; Editing by Steve Orlofsky)