Iran has agreed to resume talks with world powers on reviving a nuclear deal on 29 November after a five-month gap, with the US urging a quick resolution. The announcement of indirect negotiations in Vienna comes as pressure mounts on Iran, with western nations warning that Tehran’s nuclear work is advancing to dangerous levels and Israel threatening to attack. The EU envoy Enrique Mora, who led six rounds of talks earlier this year and recently flew to Tehran to seek progress, will again chair the 29 November meeting, the EU announced. President Joe Biden took office hoping to return to the 2015 agreement from which his predecessor Donald Trump bolted. But the talks earlier this year failed to secure a breakthrough with Iran, which requested a pause after the June election of a new hardline president, Ebrahim Raisi. In Washington, state department spokesman Ned Price said the US believed it was possible to quickly resolve the “relatively small number of issues that remained outstanding at the end of June”. “We believe that if the Iranians are serious, we can manage to do that in relatively short order,” Price told reporters. “But we’ve also been clear, including as this pause has dragged on for some time, that this window of opportunity will not be open for ever.” Trump slapped sweeping sanctions on Iran as he withdrew the US in 2018, leading Tehran to take steps out of compliance with the deal through which it had been drastically scaling back sensitive nuclear work. Iran wants a lifting of all US sanctions but the Biden administration says that it will only negotiate about measures taken by Trump over the nuclear programme, such as a unilateral ban on oil sales, not steps imposed because of concerns such as human rights. Iran also wants commitments that the United States will stay committed to the deal – an unlikely proposition in Washington, where Trump’s Republican party, emboldened by a state election win on Tuesday, fiercely opposes Biden’s diplomacy with Iran. “The American president lacks authority and refuses to offer guarantees,” Iran’s top security official, Ali Shamkhani, wrote on Twitter as the talks were announced. “If that does not change, the result of the negotiations is already clear.” The deputy foreign minister, Ali Bagheri, Iran’s lead negotiator, confirmed the 29 November resumption of talks and said the goal would be “the removal of unlawful and inhumane sanctions”. Adding to US frustrations, Iran has refused to meet directly with the US envoy, Robert Malley, so instead European mediators have to shuttle between hotels in Vienna. Britain, China, France, Germany and Russia remain in the deal with Iran and will take part in the negotiations, the EU statement said. European powers have increasingly voiced alarm at Iran’s nuclear work during the standstill in negotiations, warning that Tehran’s progress will be so advanced that a return to the agreement may be useless.