Billionaire investor Warren Buffett says he has sold his entire stake in China-based oil company PetroChina ( PTR). The chairman and CEO of Berkshire Hathaway ( BRK.A) made the comments on the sale during a televised interview on the Fox Business channel Thursday afternoon. For months, Buffett and Berkshire, along with other companies, have been targeted by social critics for holding PetroChina stakes. That's because PetroChina's government-controlled parent firm, China National Petroleum, has ties to the Sudanese government, which has been accused of being at least partly responsible for the slaughter of thousands of civilians in the Darfur region of the country. However, the Oracle of Omaha, who long defended the PetroChina investment, said during the interview that the move to unload the last of the shares was a result of the price, and that it was a "decision based on valuation." Buffett had been scaling back on his PetroChina stake for the past few months, and an Oct. 10 filing with the Securities and Exchange Commission said Berkshire owned nearly 653 million ordinary shares of PetroChina, or a 3.1% stake in the securities. The American depositary receipts of PetroChina closed at $250.72 Thursday, down 4.9% on the day, and they slipped a further 0.5% to $249.50 in after-hours trading. But they've been on a tear lately. PetroChina's U.S.-listed stock is 85% above where it closed 2006, and that gain has largely been achieved since the end of August, when the shares traded roughly at the price they finished last year.