A brief statement on an Islamist Internet site Saturday, says a militant group led by al-Qaida ally Abu Musab al-Zarqawi has killed British hostage Kenneth Bigley.
British officials say they do not find the message "credible." The kidnappers said they would release a videotape to confirm the death, but it has not yet appeared.
The same website has posted unsubstantiated claims in the past, but it also was the source of videotapes that showed the beheadings of two American engineers taken hostage with Mr. Bigley last week.
The Internet site also says militants are holding seven British troops, but the British say all of their soldiers in Iraq are accounted for.
Egypt has appealed for the immediate release of all hostages, including six Egyptians, being held in Iraq.