Iran's former president, Mahmoud Ahmadinejad, rejected curbs on its nuclear programme
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Why are all eyes on Iran's nuclear talks in Vienna?

Time is running out for world powers to strike a deal with Iran to cut UN sanctions in return for action to scale back its nuclear programme.

A deadline is due to run out at 23:00 GMT on Monday.

The BBC examines why it is so important to reach an agreement on Iran's nuclear future, as talks continue in Vienna.

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