Iranian President Mahmoud Ahmadinejad visits the Natanz nuclear enrichment facility, 350 km (217 miles) south of Tehran, April 8, 2008. Iran has begun installing 6,000 new centrifuges at its uranium enrichment plant, Ahmadinejad said on Tuesday, defying the West which fears Tehran is trying to build nuclear bombs. Picture taken on April 8, 2008. REUTERS/Presidential official website/Handout (IRAN). FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS.