Qatar’s ruler, Emir Sheikh Tamim bin Hamad al-Thani, arrived in Iran on Thursday, as the Persian Gulf state tries to help end a row between Tehran and Washington over revival of the 2015 nuclear deal.

While Iranian state media portrayed the visit as proof of Iran's expansion of ties with regional countries, a source briefed on the visit told Reuters on Sunday that the emir's trip was aimed to bring the parties to the Iran nuclear pact to "a new middle ground".

Almost a year of indirect talks between Tehran and Washington to save the pact has been on hold since March, chiefly over Tehran's insistence that the US remove the Islamic Revolutionary Guard Corps (IRGC), its elite security force, from the US Foreign Terrorist Organization (FTO) list.

Washington has made it clear that it has no such plans, while also not ruling it out.

Iran's hardline rulers believe that an uncompromising approach, spearheaded by the country's strongly anti-Western Supreme Leader Ayatollah Ali Khamenei, can force Washington to accept Tehran’s demands, Iranian officials told Reuters last month.

Under the 2015 pact, Iran curbed its sensitive uranium enrichment work, a possible pathway to nuclear arms, in return for the lifting of economic sanctions.

But in 2018, then-US President Donald Trump ditched the pact and reimposed sanctions on Iran, prompting Tehran to retaliate by gradually breaching the pact's nuclear curbs.