By Alwyn Scott

NEW YORK (Reuters) - Boeing Co posted a stronger-than-expected profit on Wednesday as its backlog of orders rose, and said its 2013 forecast "assumes no significant financial impact" from the grounding of its 787 Dreamliner jet by regulators.

Shares were up 1.6 percent at 74.80 in premarket trading.

Aviation safety agencies in the United States and Japan are investigating what caused lithium-ion batteries to burn on two 787 passenger jets earlier this month, prompting regulators to ground the planes worldwide.

Boeing said it is continuing to build the Dreamliner, but has halted deliveries, and analysts have raised concerns about the cost of the grounding and for fixing the battery problem on about 125 jets that Boeing has built so far.

"Our first order of business for 2013 is to resolve the battery issue on the 787 and return the airplanes safely to service with our customers," said Boeing Chief Executive Jim McNerney.

Net income fell to $978 million, or $1.28 per share, from $1.39 billion, or $1.84, in the year-ago period, when the company posted a special tax gain.

Analysts expected earnings of $1.19 a share in the most recent fourth quarter.

Ken Herbert, an analyst at Imperial Capital, said wider profit margins on commercial airplanes drove the company to beat analysts' expectations. But he was disappointed by the company's 2013 profit outlook of $5.00 to $5.20 a share, compared with his target of $5.60. The figures largely exclude pension charges.

Revenue for the quarter rose 14 percent to $22.3 billion.

The company said it booked 394 net aircraft orders in the quarter, and that its total order backlog was nearly 4,400 planes valued at $319 billion, a record tally.

(Reporting by Alwyn Scott; Editing by Jeffrey Benkoe)