A website posted a photograph of what it claimed was a kidnapped US soldier in Iraq, but doubts were quickly raised about its authenticity and the US military said no soldiers were missing.
An American toy manufacturer said the figure in the photo resembled one of its military action figures, originally produced for sale at US bases in Kuwait.
The statement appeared on a we site where militants' statements are often posted and was in the name of a group that has claimed previous kidnappings, the Mujahedeen Brigades.
The Arabic text, which threatened to behead the American within 72 hours, contained several misspellings and repetitions. Staff Sergeant Nick Minecci, a US military spokesman in Baghdad, said "no units have reported anyone missing."
The website photo showed a figure dressed in desert fatigues, wearing a vest and knee pads and with a gun pointed to its head. All the items are similar to ones that come in a box with the action figure, named Cody.
The figure in the photo has its arms behind its body, as if tied, and is leaned against a concrete surface. Hanging on the wall is a black piece of cloth with the Islamic profession of faith written on it in white letters.
But the figure appeared stiff and expressionless. The statement said he was named "John Adam."
Mr Liam Cusack, of the toy manufacturer Dragon Models, said the image bore a striking resemblance to the African-American version of its Cody action figure.
"It is our doll ... To me, it looks definitely like it is," Mr Cusack said.
"Everything the guy is wearing is exactly what comes with our figure. If you look at the two pictures side by side, it'd be a huge coincidence."
The company, based in City of Industry, California, produced 4,000 of the figures in 2003 for the US military for sale in its Kuwait bases. It was never sold in the United States but is traded online among collectors, sometimes to use in highly-realistic dioramas, he said.
AP