Iran started pouring concrete for a second nuclear reactor near its southern port of Bushehr in a project to expand the facility with the help of Russian engineering expertise and uranium, state TV and other Iranian media said on November 10.
Bushehr, which became the first civilian nuclear power plant in the Middle East when it came online with Russian technology in 2011, is monitored by the UN's International Atomic Energy Agency (IAEA).
Tehran says the second reactor, and a planned third reactor, will each add in excess of 1,000 megawatts to the country's power grid.
"Nuclear power provides reliable electricity...and each power plant saves us 11 million barrels of oil, or $660 million per year," Ali Akbar Salehi, head of the Atomic Energy Organization of Iran, said at a televised ceremony at which mixing trucks poured concrete into the second reactor's prepared base, according to Reuters.
The United States has spent years grudgingly accepting operation of the plant despite longstanding concerns about alleged Iranian efforts to acquire the capacity to build nuclear weapons.
Iranian officials have reportedly increased enrichment beyond levels set out in their 2015 nuclear deal with the United States and other world powers, they say, to feed the Bushehr plant.
President Donald Trump withdrew the United States from that deal, known as the Joint Comprehensive Plan of Action (JCPOA), in 2018 and has reimposed and strengthened unilateral economic and trade sanctions under a "maximum pressure" campaign targeting Iran.
Iranian officials have said they resumed enrichment of uranium at the Fordow nuclear facility on November 7 in their latest break with the terms of the JCPOA.
"It was not us who started breaking commitments, it was them who did not keep to their commitments and cannot accept the nuclear deal as a one-way road map," Salehi said at the Bushehr ceremony, according to AP.
The 4-year-old JCPOA, which Russia, China, and European powers are still trying to salvage, is an effort to curb Iran's nuclear program in exchange for international sanctions relief.
Iran long has maintained its nuclear program is for peaceful purposes, although the IAEA has accused Tehran of past deception and obfuscation over its atomic activities.
Iran's Foreign Ministry spokesman on November 10 dismissed claims by the United States and Israel over accusations of undeclared nuclear material at an undeclared site outside the Iranian capital.
An Iranian Foreign Ministry spokesman on November 10 said Tehran "has made no decision yet on leaving" the international nuclear Nonproliferation Treaty (NPT) as it rolls back its JCPOA commitments, according to Iranian state Press TV.
Also on November 10, President Hassan Rohani announced the discovery of some 53 billion barrels' worth of crude-oil deposits in southwest Iran that could boost the country's reserves by about one-third.