DOHA - Iran on Monday signalled “significant progress” in talks on reviving a stalled accord on its nuclear programme but President Ebrahim Raisi, on his first visit to a Gulf state, again insisted that the United States must lift its crippling sanctions. Iran’s ultraconservative leader, a personal target of the US sanctions, spoke out ahead of a summit of natural gas exporting nations in Qatar. The summit will take place against the backdrop of mounting tensions in Ukraine and reported advances in resuming a deal limiting Iran’s nuclear programme. The United States under former president Donald Trump withdrew from the 2015 accord in 2018, saying it was not tough enough in curtailing Iran’s weapons ambitions. Tehran has always denied seeking an atomic bomb. But months of negotiations in Vienna have brought the two sides closer to a new deal. Iran’s foreign ministry said Monday that “significant progress” has been made and the number of outstanding obstacles had been “considerably reduced”.