In a January 9, 2010 interview on Iranian TV, Iranian Atomic Energy Organization head Ali Akbar Salehi said that Iran had the right to enrich uranium to 100%, but that it nevertheless preferred to purchase the nuclear fuel it needed from other countries.
It should be noted that uranium enriched to 90% or higher is used only for military purposes, in the construction of nuclear weapons. According to International Atomic Energy Agency regulations, uranium for peaceful purposes may be enriched to no more than 5%, with prior authorization from the agency. Additionally, with the IAEA's authorization, uranium enriched to 19.75% can be used to operate research reactors for medical purposes, like the one in Tehran (this type of uranium can be purchased from countries that operate enrichment facilities).
Following are excerpts from Salehi's interview:
In response to a question about exchanging Iran's 1,200 kilograms of uranium, already enriched to 3.5%, for 120 kilograms of uranium enriched to 20%, Salehi said: "Although we informed the IAEA in advance that our centrifuges are set up in such a way that we do not enrich uranium to over 5%, we do have the right to enrich uranium to a level of up to 100%, and we will always have this right. Enrichment to a level of 20% is also within our rights, but we prefer to obtain the [nuclear] fuel from abroad."
Salehi added, "The [Western] countries that negotiated with us on the [nuclear] fuel issue asked us not to publicize [their] informal proposal for the exchange of [nuclear] fuel [meant] for the research reactor in Tehran. Publishing it could have brought us much political advantage." He said further that Iran demanded "tangible guarantees that it would [actually] receive uranium enriched to 20% in a deal of simultaneous [exchange] carried out on Iranian soil."
During the interview, Salehi reiterated several times that even though Iran had the ability to supply its own needs, it preferred to purchase the enriched uranium, so that Iran and the rest of the world could assess the sincerity of the West's proposals.
 ISNA, IRIB (Iran), January 10, 2010