TEHRAN, Sept. 7 (Xinhua) -- In a fresh move to reduce commitments to the 2015 landmark nuclear deal, Iran started up advanced centrifuges on Saturday to boost the country's stockpile of enriched uranium, state TV reported.

The Atomic Energy Organization of Iran (AEOI) activated 20 IR-4 centrifuges and 20 IR-6 centrifuges, the AEOI spokesman Behrouz Kamalvandi was quoted as saying.

"We have started lifting limitations on our research and development (R&D) program imposed by the deal ... It will include development of more rapid and advanced centrifuges," said Kamalvandi.

Iran's new move to drop limitations on its R&D will facilitate the enrichment of uranium up to a level of 1,000,000 separative work units (SWUs), he said.

SWU is the standard measure of the effort required to separate isotopes of uranium during an enrichment process. One SWU is equivalent to one kg of separative work.

The International Atomic Energy Agency (IAEA) has been informed about Iran's new nuclear steps, Kamalvandi said, adding that the IAEA will continue to monitor Iran's nuclear activities.

On Thursday, Iranian President Hassan Rouhani said that the Islamic Republic will expand its nuclear research and development to set aside the restrictions imposed on the country's research and development activities in the nuclear deal.

Despite progress in the negotiations between Iran and the European parties to the nuclear deal, "final agreement has not been reached so far" pertaining to Iran's interests under the deal, Rouhani said.

Iran has already broken away with the restrictions, set by the nuclear accord, on the stockpile of its low-grade enriched uranium and its concentration in May in a reaction to the U.S. exit from the international deal last year.

Kamalvandi said on Saturday that the cuts of commitments are reversible if other parties to the Joint Comprehensive Plan of Action fulfill their obligations.