Norwegian Foreign Minister Espen Barth Eide said the terrorists had tried to blow up the plant on Saturday but managed only to start a small fire. "That's when they started to execute hostages, and the special forces intervened," Eide said. Norway's Statoil said five Norwegians were still missing.An audio recording of Algerian security forces speaking with the head of the kidnappers, Abdel Rahman al-Nigiri, on the second day of the drama indicated the hostage-takers were trying to organize a prisoner swap. "You see our demands are so easy, so easy if you want to negotiate with us," al-Nigiri said in the recording broadcast by Algerian television. "We want the prisoners you have, the comrades who were arrested and imprisoned 15 years ago. We want 100 of them." In another phone call, al-Nigiri said that half the militants had been killed by the Algerian army on Thursday and that he was ready to blow up the remaining hostages if security forces attacked again. An organization that monitors videos from radicals posted one showing al-Nigiri with what appeared to be an explosive belt around his waist. The Algerians' use of forced raised an international outcry from some countries worried about their citizens. But French Foreign Minister Laurent Fabius said Sunday on French television: "The terrorists ... they're the ones to blame." David Plouffe, a senior adviser to President Barack Obama, said that al-Qaida and al-Qaida-affiliated groups remain a threat in North Africa and other parts of the world, and that the U.S. is determined to help other countries destroy those networks. Speaking on "Fox News Sunday," Plouffe said the tragedy in Algeria shows once again "that all across the globe countries are threatened by terrorists who will use civilians to try and advance their twisted and sick agenda." ___ Ganley reported from Paris. Associated Press writers Paul Schemm in Rabat, Morocco, and Lori Hinnant in Paris also contributed to this report.