Iran announced its Arak nuclear reactor's core vessel has been removed before UN inspectors come to control nuclear site, state television said on Thursday.
The incident confirmed the implementation of Tehran's atomic agreement with major powers, Iran state television stated.
The nuclear deal signed on July 14, 2015 in Vienna between Iran and six world powers - Britain, China, France, Germany, Russia and the United States - is aimed at monitoring Iran's most sensitive nuclear work for over 12 years in exchange for immediate relief for the country from the economic sanctions which have long crippled its economy.
Atomic Energy Organisation of Iran spokesman, Behrouz Kamalvandi, said, "The core vessel of the Arak reactor has been removed ... and International Atomic Energy Agency (IAEA) inspectors will visit the site to verify it and report it to the IAEA ... We are ready for the implementation day of the deal."
Under the historic deal, Iranian authorities hope the IAEA report concerning the international sanctions over Tehran will be announced on Friday. The UN watchdog has till now rejected to give information on the report.
According to Iranian officials, Iran's Foreign Minister Mohammad Javad Zarif and the European Union's Federica Mogherini will declare a common statement on Saturday or Sunday, the "Implementation Day" of the nuclear agreement and the lifting of sanctions.
Since 2012, the US and EU sanctions have halted around 1.5 million barrels per day (bpd) of Iranian exports, cutting down its oil exports by 60 percent to about 1 million barrels a day.
Tehran has sharply decreased the number of centrifuges established at the Fordow and Natanz enrichment sites in recent months and sent tonnes of low-enriched uranium materials to Moscow.
"The core's holes will be filled with concrete ... The core was initially supposed to be cut into parts but we did not accept it as we want to keep it as the symbol of Iran's nuclear industry," Kamalvandi told state TV.