General Mills Inc posted disappointing quarterly earnings, hurt by higher ingredient costs, and its shares fell nearly 3 percent, while rival ConAgra Foods Inc topped Wall Street's expectations.

Both packaged food companies backed their fiscal 2012 outlooks on Tuesday despite higher ingredient costs and lingering economic uncertainty.

General Mills, which makes Progresso soups and Cheerios cereal reported net income of $444.8 million, or 67 cents per share, for the second quarter ended on November 27, down from $613.9 million, or 92 cents per share, a year earlier.

Excluding the effects of accounting for commodity hedges, costs from the acquisition of Yoplait and a tax benefit, earnings were 76 cents per share.

On that basis, analysts on average were expecting 79 cents per share, according to Thomson Reuters I/B/E/S.

Sales rose 14 percent to $4.62 billion, helped by the addition of Yoplait, increases in price and volume, and foreign exchange rates.

The company affirmed its forecast for fiscal 2012, saying it still expects earnings of $2.59 to $2.61 per share, excluding items.

Meanwhile, ConAgra's earnings of 47 cents per share, excluding items, for the second quarter ended on November 27 topped the analysts' average estimate of 43 cents. The company cited strength in its commercial foods segment.

ConAgra also affirmed its full-year outlook, saying 2012 earnings should grow at a low- to mid-single-digit percentage rate from the $1.75 per share it earned last year.

The company said the outlook reflected the strong second-quarter performance as well as expectations for a 10 percent increase in costs this year and continued challenges in the business environment.

Most earnings growth in the back half of the fiscal year will be in the fourth quarter, ConAgra said.

Shares of General Mills were down 2.8 percent at $38.50 before the market opened, while ConAgra was not trading.

(Reporting By Martinne Geller in New York; Editing by Lisa Von Ahn)