Iran has decided to resume uranium enrichment activities soon despite a stern warning from the European Union and the United States against it, a top Iranian nuclear official said Thursday.

"We are going to restart a small part of the suspended nuclear activities, maybe some of those in the uranium conversion facility near Isfahan," Gholam Reza Aghazadeh, head of Iran's Atomic Energy Organization, was quoted by state television as saying.

Aghazadeh said activities related to centrifuges might also be resumed, but he did not reveal the exact date of the resumption.

Tehran is expected to submit a letter to the International Atomic Energy Agency (IAEA), the UN nuclear watchdog, on Thursday officially announcing it will resume enrichment-related activities.

This move came in defiance of a warning by Washington and the EU to refer Iran's case to the UN Security Council for possible sanctions if it resumed enrichment activities.

Iran has blamed the EU for prolonging negotiations on its disputed nuclear program and threatened to resume enrichment- related work, which it suspended in November 2004 as confidence- building measure.

The EU powers France, Britain and Germany have tried to persuade Iran to abandon its uranium enrichment program in return for economic and political incentives.

The EU shared Washington's suspicions that Iran's uranium enrichment program could be used to make nuclear weapons.

Tehran claims its nuclear program is intended only for producing fuel for power plant and it will never give up its legitimate rights to own nuclear technology.