Iranian nuclear chief "Ali Akbar Salehi" defended Tehran's "right" to carry out research on advanced centrifuges.
Iran and world powers agreed Friday on how to implement a landmark deal reached in November on containing Tehran's nuclear programme, but it must still be approved by each country before it can take effect.
Salehi was quoted as saying by Fars news agency "advanced centrifuges, which are Iran's right to use, were one of the points of disagreement raised by the other party".
Under the November deal, Tehran agreed to curb parts of its nuclear drive for six months in exchange for receiving modest relief from international sanctions and a promise by Western powers not to impose new measures against its hard-hit economy.
In August, Iran said it has about 19,000 centrifuges, including 1,000 of new P-2 generation, confirming figures from the UN watchdog overseeing its disputed nuclear drive. Iran is also developing newer generation of centrifuges which are more powerful than the previous ones.
Two days of talks between high-level Iranian and E.U negotiators ended in Geneva Friday with "very good progress on all the pertinent issues," said Michael Mann, a spokesman for EU foreign policy chief Catherine Ashton.
Iranian deputy chief nuclear negotiator "Abbas Araqchi" said "we found solutions for all the points of disagreement".