United Nations Secretary-General Antonio Guterres has urged US President Joe Biden’s administration to relax or waive all sanctions against Iran, as agreed in a 2015 agreement aimed at preventing Tehran from acquiring nuclear weapons.

Guterres also encouraged the US to “extend the waivers with relation to the trade in oil with the Islamic Republic of Iran, and completely renew waivers for nuclear non-proliferation initiatives” in a report to the UN Security Council.

The 15-member council will on Tuesday discuss the secretary-general’s biannual report on the implementation of a 2015 resolution that enshrines the nuclear deal between Iran, the United States, France, Britain, Germany, Russia and China.

Guterres’ appeal to Washington comes amid talks to revive the deal – known as the Joint Comprehensive Plan of Action – under which Iran accepted curbs on its nuclear programme in return for a lifting of many foreign sanctions against it.

Former U.S. President Donald Trump abandoned the pact in 2018 and reimposed harsh sanctions, prompting Tehran to start violating some of the nuclear limits in 2019.

“I ask to the United States to lift or waive its sanctions contained in the plan,” Guterres said, while also urging Iran to resume full implementation of the agreement.

Iran has refined uranium to a purity of roughly 60%, far exceeding the deal’s 3.67 percent limit and much closer to the 90% required for atomic bomb cores, though it maintains that it is only interested in civilian nuclear power and could quickly reverse its actions if Washington lifted sanctions and returned to the 2015 agreement.

“I continue to believe that a full reinstatement of the Plan remains the best option to ensure that the Islamic Republic of Iran’s nuclear program remains purely peaceful,” Guterres said.