Abuja - The number two in Nigeria's military government, Lieut Gen Oladipo Diya, is reported to be among 12 army officers and civilians arrested for plotting to overthrow army ruler Gen Sani Abacha. Two other officers, former ministers in Gen Abacha's government, have also been detained. Gen Abacha took over in political chaos following the annulment of an election in 1993, but he has vowed to restore power to civilians next year.