A picture released by the Iranian presidential website shows President Mahmoud Ahmadinejad with a monkey from its space program during a ceremony to mark Iran's National Day of Space Technology in Teheran on Monday. [Photo/Agencies]

Washington says photos of primate before, after flight don't match.

The United States has expressed doubt about Iran's claim that it safely returned a monkey from space, saying it is questionable that the monkey survived - or that the flight took place at all.

State Department spokeswoman Victoria Nuland said many questions remained "about whether the monkey that they reportedly sent up into space and reportedly came down was actually the same monkey, whether he survived".

She added: "The Iranians said they sent a monkey, but the monkey that they showed later seemed to have different facial features. He was missing a little wart."

Teheran blames the confusion on Iranian media for initially using a photo of a backup monkey. It said the monkey orbited and returned safely, and President Mahmoud Ahmadinejad added on Monday that he will consider being Iran's first astronaut.

Nuland described Ahmadinejad's proclamation as an "interesting choice".

Jonathan McDowell, a Harvard astronomer who tracks rocket launches and space activity, said that the monkey space flight was real. However, he had a slightly different explanation for the photo mix-up, saying the monkey with the mole died during a failed space mission in 2011.

Iran has never confirmed that a monkey died in 2011, or that there was a failed mission that year.

Teheran said its goal is a manned space flight.

Washington and its allies claim Iran's space program may be a cover for ballistic missile technology development.