Ali Akbar Salehi, the head of Iran's nuclear programme, tells Al Jazeera that it is Iran's right to refine uranium to whatever level it needs.

Saying that his scientists have the potential to enrich uranium to weapons-grade levels, he warns Barack Obama, the US president, not to test Iran, saying there could be unimaginable consequences if he takes "any wrong step".

Nazanine Moshiri has the interview. (12 Feb 2010)