Iran on Tuesday began enriching uranium to a level of 20 percent at its Natanz enrichment facility under the surveillance of inspectors from the UN nuclear watchdog.
The move comes after Iranian President Mahmoud Ahmadinejad tasked the Atomic Energy Organization of Iran (AEOI) with enriching uranium to 20 percent in order to meet the demands of the country's cancer patients.
Iran has earlier informed the International Atomic Energy Agency (IAEA) that it would start enriching uranium to 20 percent on Tuesday in the presence of the inspectors and observers from the agency.
Iran needs 120 kg (264 lb) of 20 percent-enriched uranium to fuel the Tehran research reactor, which produces medical isotopes for cancer patients and is soon to run out of fuel.
The Tehran research reactor, which produces 20 different kinds of radio-medicine for cancer patients, runs on 20 percent-enriched U-235.
The AEOI Director Ali-Akbar Salehi on Tuesday confirmed the beginning of uranium enrichment to 20 percent purity level at Natanz plant.
"The enrichment started on Tuesday in a separate cascade from the production line that enriches uranium in Natanz," Salehi told the Islamic Republic News Agency.
"We opened a new cascade, called S8, in Natanz which is more on a lab scale," he said.
The top nuclear official said that doors are still open for talks with Iran about nuclear fuel swap.
"The beginning of the enrichment is not tantamount to the end of interaction and negotiations on a UN-brokered proposal on fuel swap," he said.
"The Islamic Republic of Iran is still ready to continue cooperation if the negotiation parties act wisely and end wasting time," Salehi underlined