• * Jan data traffic through Opera browser up 18 pct m/m
• * Operators see data traffic crucial as voice revenues fall
• * Facebook, other networking services key sites on mobile

By Tarmo Virki, European technology correspondent

HELSINKI, Feb 25 (Reuters) - Global mobile data traffic through Internet browser firm Opera's mobile portal rose in January by 18 percent on the previous month, the fastest pace of growth since May 2008, Opera said on Wednesday.

Wireless operators are keen on raising revenue from Internet browsing and the social networking boom as revenue from traditional voice calls is declining.

Data traffic on mobile operators' networks rose on average 4.7 times last year, with some operators seeing traffic surge more than 10 times, boosted by the uptake of wireless data cards in laptops, according to telecoms equipment firm Nokia Siemens.

http://uk.reuters.com/article/governmentFilingsNews/idUKLP65246620090225