* 15 arrested for plotting to carry out attacks
* Group members allegedly trained by Somalia's al Shabaab
* Suspects said to have entered from Somalia, Kenya
By Aaron Maasho
ADDIS ABABA, Jan 2 (Reuters) - Ethiopian police have arrested 15 suspected militants allegedly trained by Islamist rebels in neighbouring Somalia and who were plotting attacks in Ethiopia, the country's intelligence agency said on Wednesday.
The arrests were the latest in a crackdown on what senior officials say is a growing threat from militant Islam in Ethiopia, a Horn of Africa nation predominantly comprised of Orthodox Christians and a large minority of Muslims.
The would-be militants were caught following a 20-day sting operation while they plotted to set up cells in the eastern town of Harar and in Kemise in the northeast, the National Intelligence and Security Service (NISS) said.
"Members of the group were recruited, trained and armed by Somalia's al Shabaab and their aim was to wage Jihad (holy war) and stage attacks inside the country," an NISS statement said, aired by the state-run Ethiopian Television.
Addis Ababa has sent troops to Somalia to help other African countries battling to crush al Shabaab's six-year insurgency.
The suspects, whose nationalities were not disclosed, were said to have crossed into Ethiopia from Somalia and Kenya.
Wednesday's TV report showed police displaying large amounts of arms including rifles and grenades, as well as black flags with Arabic inscriptions. The report said CDs and video tapes of "jihadist messages" were also seized during the operation.
On Tuesday, an Ethiopian court convicted 10 other militants of preparing strikes on political and economic targets in Ethiopia with the help of Somalia's al Qaeda-allied al Shabaab.
Muslims in Ethiopia staged several mass protests last year against perceived interference in Islamic affairs. Several leaders of a committee that led the protests now face trial.
Ethiopia fought Islamist rebels in Somalia in 2006-2009 and sent troops back in 2011 to fight al Shabaab, opening a third front alongside Kenyan troops and an African Union mission.
The onslaught on rebels in Somalia has gained ground in the past two years. Al Shabaab withdrew from the southern port of Kismayu in September, its last major urban stronghold, heralding its demise as a quasi-conventional military force. (Editing by Richard Lough and Alistair Lyon)