Iran, which wants international sanctions that have crippled its economy lifted in exchange, has always insisted that its nuclear work is peaceful.

Sticking points are still reported to be how sanctions are lifted and the amount of nuclear capability Iran is allowed to keep.

'Coercion'

Iran's Foreign Minister Javad Zarif said on Friday that Iran was ready to strike a deal and negotiators had "never been closer to a lasting outcome".

But in a video message he also called for an end to "coercion and pressure" at the nuclear talks.

Will deal be Iranian president's legacy?

Iran's Supreme Leader Ayatollah Ali Khamenei, who has the final say on all Iranian state matters, last week rejected some key demands of the P5+1, insisting Iran would only dismantle its nuclear infrastructure if the sanctions were lifted first.

The deadline for reaching a comprehensive agreement on Tehran's nuclear programme has already been extended from the 30 June.