UPDATE 1-Norwegian Air raises guidance after surprise Q4 profit

OSLO Feb 15 (Reuters) - Fast-growing budget airline Norwegian Air has raised its growth outlook for 2013 after a surprise pretax profit for the normally weak fourth quarter.

The company said it now expects to increase its capacity, in terms of available seat kilometres (ASK), by more than 25 percent this year, including new long haul routes. Previous guidance was for ASK growth in excess of 20 percent.

Norwegian Air has 276 Boeing and Airbus aircraft on order for delivery over the next decade.

Pretax profit for the last three months of 2012 came in at 23 million crowns ($4.17 million). That compared with a 188 million crown loss a year earlier and comfortably beat the average estimate of a 53 million crown loss in a Reuters poll of analysts.

Chief Executive Bjoern Kos said earnings should improve once costs decline. "The result should have been much better," he told a news conference.

Shares in the company rose 2.3 percent by 0835 GMT, outperforming a 0.1 percent decline in the Oslo benchmark index .