Iran and the P5+1 group of nations (China, the United States, France, Britain, Russia and Germany) have set a November 24 deadline to strike a deal guaranteeing that Tehran's nuclear programme is used for exclusively peaceful means.
But talks have stalled over the issue of Iran's future capacity for uranium enrichment and the timetable for the lifting of international sanctions against Tehran.
"I think that before the end of next week we will have bilateral and multilateral negotiations in Vienna," foreign ministry spokeswoman Marzieh Afkham said on Wednesday.
"The exact date will be given later," she added.
An infographic published on Khamenei's official website outlined 11 points to be observed by negotiators before Iran will sign an accord.
One of the stipulations includes "the absolute need for Iran's uranian enrichment capacity to be 190,000 SWU (Separate Work Units)" -- close to 20 times its current processing ability.
Iranian officials say this is needed to produce fuel for its Bushehr reactor, which is being provided by Russia until 2021.
"Fordo, which cannot be destroyed by the enemy, must be preserved," the text on Khamenei's website said, referring to the uranium enrichment site built under a mountain 100 kilometres (60 miles) south of Tehran.
"The work of nuclear scientists should in no way be stopped or slowed," the text said, adding that Iran had the right to pursue nuclear "research and development".
Iran and the so-called P5+1 group signed a preliminary accord in September 2013 that cleared the way for certain Iranian nuclear activities in exchange for a partial lifting of international sanctions.
The Vienna-based UN nuclear watchdog, the IAEA, disclosed last month that Iran had failed to meet an August 25 deadline to provide information on five points meant to allay fears it was developing nuclear weapons.
Eight days of intensive talks at the end of September between Iran and the P5+1 group on the sidelines of the UN General Assembly in New York also fell short of any final agreement.
Iran insists its nuclear programme is entirely peaceful.
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