Kenya mobile penetration crosses 50 pct mark-govt

* 19.9 million SIM cards

* Internet usage boosted by 3G service

NAIROBI, Aug 23 (Reuters) - Mobile phone penetration in Kenya was 51 percent mark in the first quarter of 2010 when SIM card numbers rose 2.7 percent to 19.9 million from the previous quarter, the industry regulator said on Monday.

“The growth in the number of mobile subscriptions can be attributed to multiple SIM ownership and increased number of service providers offering attractive promotions,” Communications Commission of Kenya (CCK) said in a quarterly report.

Tariffs fell during the quarter as Kenya’s four operators offered incentives in a bid to retain subscribers and attract new ones.

Mobile traffic increased by 20 percent to 5.1 million minutes as users increased and tariffs declined, CCK said.

Last week, CCK halved interconnection rates with the aim of increasing mobile phone usage.

The second largest operator, Zain ZAIN.KW slashed its tariff to 3 shillings per minute, which most Kenyans hope will spark a price war with market leader Safaricom SCOM.NR.

Internet users jumped nearly 60 percent to 6.4 million chiefly due to mobile phone data services through 3G networks, CCK said. Most of it was activity on social networking sites mainly by young people. (Reporting by Helen Nyambura-Mwaura; Editing by David Cowell)