Around 40 hostages from at least 12 countries are reportedly being held captive by insurgents in Iraq.

Coalition spokesman Dan Senor said Wednesday that the U.S. Federal Bureau of Investigation was investigating the spate of abductions but reiterated there would be no negotiations with kidnappers, who have demanded the withdrawal of foreign troops.

Meanwhile, Japan's Asahi Shimbun newspaper said Iraqi insurgents who are holding three Japanese hostages are using the Japanese as a negotiating chip with the U.S., which has resumed its offensive in Fallujah, west of Baghdad.

Chief Cabinet Secretary Yasuo Fukuda said that Japan is doing all it can to ensure the safe release of the hostages, but nothing about their fate had been confirmed.

A group of kidnappers, calling itself the "Mujahedeen Brigades," has threatened to kill the Japanese hostages unless Tokyo withdraws 550 troops from the southern Iraq town of Samawa.