"With the new machines, which have been installed after taking the third step [to reduce Iran's commitments under the deal], 2,600 SWU (separative work units) have been added to the country's enrichment capacity," Press TV quoted Behrouz Kamalvandi, the spokesman for the Atomic Energy Organization of Iran (AEOI), as saying in an interview on Thursday.
The nuclear deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), was reached in Vienna in July 2015 between Iran and the P5+1 group of states the US, the UK, France, Russia, and China plus Germany.
It lifted nuclear-related sanctions against Tehran, which, in turn, voluntarily changed some aspects of its nuclear energy programme.
The US, however, left the accord last May and reinstated its unilateral sanctions against Iran.
In response, Iran initiated a first step in reducing its obligations under the JCPOA this May by increasing its enriched uranium stockpile to beyond the 300-kg limit set by the agreement.
In the second step, Tehran began enriching uranium to purity rates beyond the JCPOA-limit of 3.76 per cent.
The third bout had the country start up advanced centrifuges to boost its stockpile of enriched uranium and activate 20 IR-4 and 20 IR-6 centrifuges for research and development purposes.
On Tuesday, President Hassan Rouhani announced the fourth step, saying that Tehran would begin to inject uranium hexafluoride (UF6) gas into centrifuges at its Fordow enrichment facility on Wednesday, as a third 60-day deadline for the European co-signatories to fulfil their side of the deal expired.
Located in central Iran, Fordow houses 1,044 centrifuges, said Press TV.
Meanwhile, Kamalvandi said on Thursday: "A total of 15 new machines were installed after the third step, which increased our total nuclear production capacity to 2,600 SWU. Today, the work at Fordow has been finished and four more cascades will be added to increase our total capacity by about 700 SWU.
"When the work is totally done, our overall (enrichment) capacity will stand at about 9,500 SWU, which is the level we held before singing the JCPOA."
( With inputs from IANS )