Fighting in Ethiopia's volatile eastern Somali region over the weekend has left an unknown number of civilians dead and thousands displaced, the patriarch of Ethiopia's Orthodox church told state media on Monday.It was unclear what sparked the clashes in Ethiopia's second-largest region, but it appeared to start after the arrival of troops in the regional capital Jijiga.On Saturday the US embassy said the Ethiopian military had "seized control of key highways, government buildings, and the airport in Jijiga" and warned its citizens to steer clear of the region.Residents later told AFP mobs in the regional capital were looting banks and businesses and targeting people from outside the Somali ethnic group.On Monday, Abune Mathias, patriarch of the Ethiopian Orthodox Tewahedo Church said churches and priests were harmed in the violence."A total of seven churches were set ablaze and priests killed in the attacks. Civilians were also killed and thousands displaced," Abune Mathias told state-affiliated Fana Broadcasting Corporate.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africaon Twitter and FacebookA spokesperson for the church had no further details on numbers of dead and displaced.Ethiopia is divided between ethnically demarcated federal regions that are intended to give different ethnicities a degree of self-rule but have been criticised for exacerbating ethnic tensions.Rashid Abdi, Horn of Africa director at the International Crisis Group (ICG) think tank in Nairobi, said on Twitter the violence appears to result from a standoff between the Ethiopian federal government led by Prime Minister Abiy Ahmed and the Somali regional authorities.Rights groups have repeatedly accused the regional government led by president Abdi Iley of committing rights abuses.Last month, Human Rights Watch said regional authorities ran a secret jail where suspected members of a separatist group are tortured, raped and starved.Abdi of the ICG said Abiy's predecessors had relied on the regional president to pacify the Somali region and keep Islamist Al-Shabaab militants in neighbouring Somalia from entering Ethiopia. But since taking office, Abiy has announced major reforms that Somali regional authorities believe would disrupt their hold on power, Abdi said."They distrusted his reform agenda, concluded he was intent on disrupting the cosy arrangement that allowed the (Somali region) leader untrammelled power," Abdi said."The political rewards of (Abdi) Iley's ouster is uncertain while the security risks obvious. A political vacuum is a real risk," he added.