Iran's President Ebrahim Raisi, on a trip to Qatar, said on Monday the United States should prove its will to lift sanctions in indirect talks to salvage a 2015 nuclear pact.
Raisi's trip to Doha comes amid progress in Vienna towards reviving the deal between Iran and world powers, that Washington quit in 2018, in talks being closely watched by Gulf states concerned about Iran's missiles programme and regional proxies.
"Guarantees are essential to reach an agreement in the nuclear talks," Raisi said at a joint news conference with Qatar's Emir Sheikh Tamim bin Hamad al-Thani.
The emir, whose foreign minister recently held talks in Washington and in Tehran, said his U.S.-allied country was ready to do what it can to help bring an agreeable solution to all parties in Vienna.
Earlier, Qatar and Iran signed bilateral agreements in the first visit by an Iranian president to Doha in 11 years, during which Raisi will attend a gas exporters summit on Tuesday.
"We have today expanded our cooperation in the fields of economy, energy, infrastructure, culture and food security," the president said.
Before heading to Qatar, Raisi expressed hope his visit would boost ties with other Gulf Arab states and stressed Iran's status as a main oil and gas producer and founding member of the Gas Exporting Countries Forum.
Iran's oil minister said on Monday that unilateral sanctions against members of the forum threaten global energy security and that Iran provided the best option for gas exports to east and west, the semi-official Tasnim news agency reported.
Qatar has good ties with Iran, with which it shares a giant gas field. Tehran supported Doha after Saudi Arabia and its Arab allies imposed a boycott on Qatar in mid-2017 in a dispute over its ties with Islamist groups and non-Arab Turkey and Iran.
The Gulf row was resolved early last year and Gulf powerhouse Saudi Arabia, which is locked in several proxy conflicts with Iran including in Yemen, has been engaging directly with Tehran in a bid to contain tensions.
Iran has faced gas shortages at home because of record high consumption particularly for winter household heating and has had to cut supplies to cement plants and other industries.
(Reporting by Dubai Newsroom, Lina Najem and Nadine Awadalla, Writing by Ghaida Ghantous; Editing by Lincoln Feast and Emelia Sithole-Matarise)