ADDIS ABABA (Reuters) - Somali authorities have handed over to Ethiopia a senior official of the ONLF rebel group, which is fighting for the secession of Ogaden from Ethiopia, the group said. Abdikarin Sheikh Muse, an executive committee member who lived in the Somali capital Mogadishu, was detained by security in Galkayo in Somalia s semi-autonomous Galmudug state on August 23, the ONLF said in a statement. Quoting sources close to the Somali cabinet, it said the Somali government had  forcefully  handed over Abdikarin Sheikh Muse to Ethiopia without his consent in violation of U.N. convention relating to the status of refugees. Ethiopian officials were not available for comment.  The Ogaden National Liberation Front (ONLF) launched its bid for secession of the Somali Region, also known as Ogaden, in eastern Ethiopia in 1984. In 2007, Ethiopian forces waged a large-scale offensive against them after the group attacked a Chinese-run oil facility, killing 74 people. Analysts say the rebels have since been severely weakened but are still able to launch hit-and-run attacks. The region they operate may contain 4 trillion cubic feet of gas and major oil deposits, mining experts say. China s GCL-Poly Petroleum Investments signed a production sharing deal with the government in late 2013 to develop two gas fields. 