Warren Buffett's Berkshire Hathaway Inc said on Tuesday Comcast Corp Chief Operating Officer Stephen Burke has been elected to its board of directors.

Burke would bring to 12 the number of directors on the board, which has attracted increasing attention in the last few years as investors wonder about Buffett's succession plan.

A Berkshire spokeswoman did not say whether Burke would replace another director.

Burke, 51, is business-savvy, owner-oriented and keenly interested in Berkshire, the three ingredients we look for in directors, Buffett said in a statement.

Burke also serves on the board of JPMorgan Chase & Co , and should have his hands full following this month's deal that gives Comcast a majority stake in NBC Universal.

He joins a board that last month approved a 50-for-1 split of Berkshire's class B common stock related to the planned $26.4 billion takeover of railroad operator Burlington Northern Santa Fe Corp .

Buffett, 79, earlier this year told Berkshire's annual shareholder meeting he has three internal candidates in mind to succeed him as chief executive.

The CEO has not hinted when he will quit, but the succession issue has cast new light on a board that some in the past have criticized as having too many insiders, despite the company's success.

Burke's appointment could temper some of that criticism and diversify thinking on the board, said Bob Monks, a shareholder rights activist.

The question is not who should replace Buffett to run Berkshire, Monks said, but rather what combination of wisdom will figure out the best thing to do with the assets that now constitute it.

That's the context in which you want to make new additions to the board, said Monks, who has written 10 books on corporate governance.

By virtue of reaching out and getting clearly intelligent, younger, interested people with a variety of experience, this expresses a sense that what's needed is ... a wider view of how this can be managed.

In 2007, Berkshire appointed to its board Susan Decker, 46, Yahoo Inc's former chief financial officer. Other directors include Microsoft Corp founder Bill Gates, 54; former Coca-Cola Co President Donald Keough, 83; and Berkshire Vice Chairman Charles Munger, 85.

Berkshire's Class B shares slipped $1.95 to $3,297.00 on the New York Stock Exchange late Tuesday afternoon.

(Reporting by Jonathan Spicer; Editing by Gerald E. McCormick and Richard Chang)