Iran will not agree to ship out its stockpile of enriched uranium, one of its main negotiators said Sunday ahead of crunch talks with world powers on its nuclear programme.

"We will negotiate about the volume, levels and the methods of enrichment but shipping out the (enriched) material is a red line for Iran," deputy foreign minister Abbas Araqchi told the state broadcaster.

The remarks came on the eve of two-day talks in Geneva, the first meeting between Iranian negotiators and world powers since President Hassan Rouhani, a reputed moderate, took office in August.

The red line adds to Tehran's insistence on what it considers its "right" to a uranium enrichment programme on its soil -- a process that can fuel civilian objectives but, in its more advanced form, yield the fissile core of a bomb.

Iran currently has a stockpile of 6,774 kilogrammes of low-level uranium enriched, and nearly 186 kg of medium-enriched material with 20 percent purity, according to latest figures by the UN nuclear watchdog in September.

It also possesses some 187 kg of the 20 percent material converted to uranium oxide for use in fuel plates.

The UN Security Council has demanded that Iran suspend uranium enrichment and has imposed crippling sanctions on the country.

Araqchi said Iran would "remove all of (the) rational concerns of the other side," referring to suspicions in the West and Israel that Tehran is pursuing nuclear arms under the guise of a civilian energy programme, a claim the Islamic state vehemently denies.

"They always claim that they are not opposed to a peaceful nuclear energy (programme) in Iran but are against nuclear weapons," Araqchi said.

"When we give them the confidence that Iran has no (nuclear) military programme on its agenda, they will have their victory."

As for Iran, he said, the Islamic state's objective is the recognition of "its rights in the field of enrichment."

"We will not back down one iota from what the Iranian people are entitled to under international regulations," he added.

Foreign Minister Mohammad Javad Zarif is Iran's top negotiator with the so-called P5+1 group of the United States, Britain, China, France and Russia plus Germany.

But Araqchi said he will lead the Iranian team in the talks with European Union foreign policy chief Catherine Ashton and representatives from the P5+1 countries as Zarif will only attend the opening meeting.

"The Iranian negotiating team will present a specific plan ... which we hope will produce results in a logical time period," Araqchi said.

A source close to Iranian negotiators earlier told the official IRNA news agency that Iran's proposals envisage "a clear path" for the talks, and include a timetable and a framework with "specified first and last steps."

"The intermediate steps will be defined after the first ones are taken," the unnamed source said, adding that the proposal would be presented in PowerPoint.

The talks in Geneva come amid raised hopes of a diplomatic resolution to the decade-long standoff following pledges made by Rouhani to engage with the major powers in order to secure the lifting of the sanctions.

However Rouhani's diplomatic outreach to the West has provoked criticism from hardliners, including the commander of the powerful Revolutionary Guards, General Mohammad Ali Jafari, who has questioned the president for holding an historic telephone call with US President Barack Obama.

Jafari on Sunday renewed his hardline position with an ambiguous warning, saying: "It is not in the offing that we must relinquish our rights."