Sprint Nextel posted a 6 percent increase in quarterly revenue, and it added mobile subscribers for the first quarter in more than three years, sending its shares up nearly 4 percent in early trade.

The No. 3 U.S. mobile service said it had added 58,000 contract customers in the quarter, ahead of the average expectation for almost 17,000 customer additions from eight analysts contacted by Reuters.

Sprint's loss narrowed slightly to $929 million, or 31 cents per share, in the fourth quarter from $980 million, or 34 cents per share, a year earlier.

Revenue rose to $8.3 billion from $7.87 billion and exceeded the analysts' average estimate of $8.15 billion according to Thomson Reuters I/B/E/S.

Sprint shares rose to $4.52 in early trading after closing at $4.35 in the regular New York Stock Exchange session.

(Reporting by Sinead Carew; editing by Lisa Von Ahn)