Addis Ababa -- A group of unidentified gunmen attacked a Chinese oil company's working field in Ethiopia's Somalia state early Tuesday morning, and there were casualties, an official from the Chinese Embassy in Ethiopia confirmed on Tuesday.

The Xinhua report said the oil field was in Somalia state, one of nine states making up Ethiopia.

Ethiopia is heavily involved in the violence in the neighboring country of Somalia, where Ethiopian troops are backing government forces in a fight with insurgents.

Chinese oil workers have also been targeted in Nigeria by armed militants. In March, two Chinese workers were kidnapped in Nigeria. In January, nine Chinese oil workers were taken when gunmen stormed the government-owned Chinese National Petroleum Co. office in Nigeria's state of Bayelsa.

In another incident in southern Nigeria's Rivers state the same month, five Chinese telecommunication workers were kidnapped and safely returned within two weeks.