A Web site's claim that a U.S. soldier was being held hostage in Iraq (search) is probably a hoax, senior Pentagon officials told FOX News on Tuesday.

The claim, posted on an Arabic Web site frequented by militants, was first cast into doubt when a military spokesman in Baghdad said the kidnapping claim and photo could not be verified, and that "no units have reported anyone missing."

Then later, a toy manufacturer said the figure in the photo resembled one of its military action figures, dubbed "GI Cody."

It is feasible the claim was posted in Iraq, since "Cody" is sold at U.S. bases in Kuwait.

Pentagon officials, who launched an investigation when the abduction claim came to light, believe the image of a hostage on the Web site is actually little "Cody."

The posting included a threat to kill the purported soldier if Iraqi prisoners were not released.

"God willing, we will behead him if our female and male prisoners are not released from U.S. prisons within the maximum period of 72 hours from the time this statement has been released," said the statement, signed by the "Mujahedeen Brigades" (search), a group that has claimed previous kidnappings.

Whoever posted the claim also indicated more American hostages had been taken.

"Our mujahedeen heroes of Iraq's Jihadi Battalion were able to capture American military man John Adam after killing a number of his comrades and capturing the rest," the post said.

"John Adam" would be killed in 72 hours if Iraqi prisoners were not released, the site threatened.

But there were no initial reports of any soldiers missing, and Pentagon officials said it was unlikely that a group of soldiers could be captured without anyone noticing.

The Web posting included a photo of a figure in desert fatigues with his hands tied behind his back. It was wearing a vest and knee pads with a gun pointed to its head — all similar to items that come with the action figure, "Cody."

The figure was seated before a black piece of cloth emblazoned with the Islamic proclamation: "There is no god but God and Muhammad is His prophet."

But the Arabic text contained several misspellings and repetitions. In addition, the face in the photo seemed eerily blank and emotionless.

Liam Cusack, of Dragon Models USA Inc., said the image of the soldier portrayed in the photo bore a striking resemblance to the African American version of its "Cody" action figure.

"It is our doll ... to me it definitely looks like it is," Cusack told The Associated Press. "Everything the guy is wearing is exactly what comes with our figure."

He said the figures were ordered by the U.S. military in Kuwait for sale in their bases, "so they would have been in region."

If the hostage claim turns out to be a hoax, it wouldn't be the first since the war began.

In May, a 22-year-old San Francisco game designer faked his own beheading, blamed on Iraqi militants, and made the video available on the Web. Media outlets picked up the story in August, believing it to be authentic.

After it became clear the beheading was a hoax, Benjamin Vanderford (search), an anti-war aspiring politician, was investigated by the FBI.

Marine Cpl. Wassef Ali Hassoun (search) also made headlines when he disappeared from Fallujah in June of last year. He mysteriously turned up a couple weeks later, claiming to have been kidnapped.

But a military probe concluded Hassoun had abandoned his post. He was charged with desertion in December, and once again in January after he failed to report back to base. He has since been declared a fugitive.

There have been no confirmed cases of U.S. soldiers taken hostage and killed by terrorists since the war began.

U.S. Army Spc. Keith M. Maupin (search), 20, is believed to have been taken hostage by insurgents after disappearing in a convoy attack last April. The Batavia, Ohio, native is considered missing after a tape purporting to show him being killed could not be authenticated by the U.S. Army.

FOX News' Bret Baier and Jane Roh and The Associated Press contributed to this report.