Billionaire investor Warren Buffett said the U.S. economy remains in recession, disputing this week's assessment by a leading arbiter of economic activity that the downturn ended more than a year ago.

"We're still in a recession," Buffett told CNBC television in an interview broadcast on Thursday. "We're not gonna be out of it for a while, but we will get out."

On Monday, the National Bureau of Economic Research said the world's largest economy ended an 18-month recession in June 2009, but cautioned that its assessment did not mean normal activity had resumed.

Buffett said he defines a recession differently from the NBER, saying it ends when real per capita gross domestic product returns to its pre-downturn level.

President Barack Obama said on Monday that economic weakness is "still very real" for the millions of Americans who are out of work, have seen the value of their homes fall, or are mired in debt.