Iran begins construction of 2nd nuke reactor in Bushehr

Iran has started constructing the second nuclear reactor at its power plant in the port city of Bushehr, a facility that will be fuelled by the uranium enriched further than the limits outlined by the faltering 2015 nuclear deal.

While celebrating the start of construction on Sunday, Iranian officials condemned the United States pressure campaign of sanctions that has blocked Tehran from exporting its crude oil to other nations, Al Jazeera reported.

Trucks with spinning concrete mixers poured their slurry into the prepared base of the second reactor as journalists watched in Bushehr, some 700 kilometres south from Tehran.

Officials were also quoted as saying that a third reactor is further being planned to be built - will each add more than 1,000 megawatts to Iran's power grid.

The second reactor is being built with the help of Russia, which helped to finally put Bushehr's first reactor online in 2011. It should be noted that the reactor also works with uranium produced in Russia, not Iran.

"Nuclear power provides reliable electricity ... and each power plant saves us 11 million barrels of oil or $660m per year," Ali Akbar Salehi, head of the Atomic Energy Organization of Iran, said in a televised ceremony.

Bushehr is being monitored by the United Nations' International Atomic Energy Agency (IAEA). However, Iran began 4.5 per cent enrichment in part to supply Bushehr despite the deal limiting it to 3.67 per cent.

While that is still nowhere near weapons-grade levels of 90 per cent, nonproliferation experts warn Iran's growing stockpile and increasing enrichment will begin to shave off time from the estimated one year Tehran would need to gather enough material for an atomic bomb.