DUBAI- Iran said on Monday it would take another step away from the 2015 nuclear deal by developing centrifuges to speed up its uranium enrichment, its nuclear chief Ali Akbar Salehi said.

"Today, we are witnessing the launch of the array of 30 IR-6 centrifuges," Salehi, who heads Iran's Atomic Energy Organization, told state television. "Iran now is operating 60 IR-6 advanced centrifuges. It shows our capacity and determination."

Under the agreement between Iran and world powers, Tehran is only allowed to enrich uranium with just over 5,000 of its first-generation IR-1 centrifuges. An IR-6 centrifuge can enrich uranium 10 times faster than the IR-1s.

"Our scientists are working on a prototype called the IR-9, that works 50 times faster than the IR-1s," Salehi said.

The deal was aimed at extending the time Iran would need to obtain enough fissile material for a nuclear bomb, if it sought one - something sometimes referred to as “breakout time” to about a year from 2-3 months. Iran denies ever having sought to build a nuclear bomb.

The U.N. nuclear watchdog said in September that Iran had informed the agency about making modifications to accommodate cascades - or interconnected clusters - of 164 of the IR-2m and IR-4 centrifuge. Cascades of the same size and type were scrapped under the deal.

Tensions have risen between Tehran and Washington since last year when U.S. President Donald Trump withdrew from the accord under which Iran had agreed to rein in its nuclear programme in exchange for relief from economic sanctions.

The United States has since renewed and intensified its sanctions, slashing Iran's crude oil sales by more than 80%.

Responding to Washington's "maximum pressure", Iran has breached the restrictions of the deal step-by-step and has rejected the United States' demand that a far-reaching deal should be negotiated.

Tehran, however, has left room for diplomacy by saying that talks are possible if Washington lifts all the sanctions and returns to the nuclear deal.

Iran has said it might take further steps in November if European parties to the pact fail to shield its economy from U.S. penalties.

While steps taken by Iran so far do not make a big difference to that breakout time for now, it further complicates the prospects of saving the accord by the European parties to the deal, who have criticised Trump for exiting it.

(Additional reporting by John Irish in Paris Writing by Parisa Hafezi, Editing by Angus MacSwan) ((parisa.hafezi@thomsonreuters.com;))