Iran can resume high-level uranium enrichment within five days if the United States tears up the nuclear deal, the head of its Atomic Energy Organisation said Tuesday.

"If we make a determination, at most in five days we can start 20 percent enrichment in Fordo (nuclear plant)," Ali Akbar Salehi said in an interview with state broadcaster IRIB.

"Of course we would not like such a thing to happen as we made a lot of effort to achieve the JCPOA (nuclear deal)," he added.

The 2015 nuclear deal with world powers saw sanctions eased in exchange for curbs to Iran's nuclear programme.

That included a ban on high-level enrichment of uranium of 20 percent or more -- a process which would take Iran close to the level needed for a nuclear weapon.

US President Donald Trump repeatedly threatened to tear up the nuclear deal during his campaign, and it has come under mounting pressure after Tehran carried out missile tests and Washington imposed new sanctions -- with each accusing the other of violating the spirit of the agreement.

Source: AFP