Kidnappers holding two German oil workers captive in Nigeria's Niger Delta area have demanded a ransom of USD 20 million (EUR 16.6 million), it was reported on Thursday. The abductors are also reported to have demanded that multinational oil concern Shell step up efforts to assist the poverty-stricken local population. "If the SPDC Shell Petroleum Development Company of Nigeria does not comply immediately, we are going to take over all the oil installations," Nigeria daily This Day quoted a member of the kidnap gang as saying. The two Germans, employees of a Mannheim-based company sub- contracted by Shell, were seized along with four Nigerian co-workers while travelling in a boat to a platform operated by the oil giant.