ADDIS ABABA, Oct 21 (Reuters) - Ethiopia's Ogaden National Liberation Front (ONLF) rebels said they killed 140 government soldiers in an assault targeting a visiting senior official. The rebels, who want more autonomy in their eastern region of Ethiopia bordering Somalia, said the attack on Saturday wounded other troops protecting the senior official and resulted in the seizure of ammunition and other military hardware. "This operation was a direct response to the burning of Caado village recently and the continuing abuses against the people of Ogaden," the ONLF said in a statement on Sunday. The Ethiopian government had no immediate comment.