The negotiations — attended by China, France, Germany, Russia, the United Kingdom, Iran and the United States — will resume in Vienna on Tuesday after being halted at the end of last month.

They come after parties in recent weeks cited progress in seeking to revive the 2015 Joint Comprehensive Plan of Action (JCPOA) that was supposed to prevent Iran from acquiring an atomic bomb, a goal it has always denied pursuing.

Former US president Donald Trump unilaterally withdrew from the pact in 2018 and reimposed tough economic sanctions on Iran, prompting the country to begin pulling back from its commitments under the deal and step up its nuclear activities.