The White House says it cannot confirm a statement from Iraqi kidnappers that they have killed American hostage Ronald Schulz.
In an Internet statement Thursday attributed to the Islamic Army in Iraq, the group said they had killed the American security consultant and would release photos of his killing shortly.
On Tuesday, the al-Jazeera network aired a video of the security consultant. His captors said they would kill him in 48 hours unless all prisoners in Iraq were released.
Mr. Schulz's family said they were almost certain the man pictured was their relative.
A different group is holding four Western peace activists. That group said Thursday they would extend until Saturday a deadline to kill them unless all Iraqi prisoners are released.
Earlier, a suicide bomber blew himself up on a Baghdad bus, killing at least 30 other people. The bus was to depart for the Shi'ite city of Nasiriyah.
Some information for this report provided by AFP, AP and Reuters.