A missing Iranian nuclear scientist has appeared in two different videos, each offering contradictory accounts of his whereabouts.br br The videos emerged on the eve of a UN Security Council vote on a fresh round of sanctions over Iran's nuclear programme.br br In one, released by Iranian state television, a man said to be Shahram Amiri says he was kidnapped by US intelligence agents during a religious pilgrimage in Saudi Arabia, a claim the US has denied.br br In the other, a man who also identifies himself as Amiri, says he is freely living in the US, pursuing an advanced degree in physics.br br Al Jazeera's Patty Culhane reports.