Iran has enriched uranium to 60 percent purity, Ali Akbar Salehi, head of the Atomic Energy Organization of Iran, said Friday, according to state-run media.

It marks a serious violation of a 2015 nuclear deal with world powers under which Iran's enrichment had been capped to 3.67 percent and quickly brings the purity of its enriched uranium closer to weapons-grade levels.

The inside of Iran's Natanz nuclear facility shown to the Iranian media in May 2019. (Photo courtesy of the Atomic Energy Organization of Iran)(Kyodo)

Sixty-percent purity would be the highest level ever achieved under Iran's nuclear program.

Iran's move comes as parties to the 2015 nuclear agreement and the United States have started substantive discussions in Vienna with the objective of finding a way for Washington to re-enter the agreement it withdrew from in 2018.

Iran on Wednesday started working on enriching uranium to 60 percent purity in Natanz in central Iran as a response to a sabotage on Sunday of the country's nuclear facility there it has blamed on Israel.