Iran's president has unveiled new "third-generation" centrifuges that its nuclear chief says can enrich uranium much faster than current technology.
The centrifuges would have separation power "six times that of the first generation", Ali Akbar Salehi said in a speech marking National Nuclear Day.
Uranium enrichment is the central concern of Western nations negotiating with Iran over its nuclear programme.
Jon Leyne explains what the centrifuges can do.
One-Minute World News 
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