Iran will continue to enrich uranium to 20% purity even after sanctions are lifted and the 2015 nuclear deal is revived, the country's nuclear chief said Friday.

"(Uranium) enrichment ... continues with a maximum ceiling of 60%, which led Westerners to rush to negotiations, and it will continue with the lifting of sanctions by both 20% and 5%," the head of Iran's Atomic Energy Organization, Mohammad Eslami, was quoted by the semi-official news agency Fars as saying.

The 2015 deal, known as JCPOA, restricts the purity to which Iran can enrich uranium to 3.67%, far below the roughly 90% that is weapons-grade or the 20% Iran reached before the deal. Iran is now enriching to various levels, the highest being around 60%.

Iran began exceeding the JCPOA enrichment limit up to 20 percent purity after the United States withdrew from the agreement in 2018 and imposed sanctions on Tehran.

After US elections in 2020, Iran raised the enrichment level to 60 percent, once the US signaled it was ready to start negotiations to return to the JCPOA.

Reuters reported last week that a draft agreement partially ready after more than 10 months of talks in Vienna stipulates that Iran will return to 5 percent enrichment and the US would start loosening sanctions.