Tehran (dpa) - Iran is optimistic about the further course of negotiations of a nuclear deal with world powers, which are to be continued in Vienna next week.

"We are about to get out of the impasse," said Iran's nuclear chief Ali Akbar Salehi, the news portal Entechab reported on Saturday.

He added that the reason for this is that the agenda of the negotiations is no longer being pursued politically, but technically and objectively.

On Friday, there was a video conference between Iran and the five remaining parties to the 2015 Vienna nuclear agreement - China, Germany, France, Britain and Russia.

All six parties agreed that negotiations to save the nuclear deal and a possible return of the United States would continue.

Teams of experts will meet in Vienna on Tuesday. US representatives will also take part in the negotiations, at least indirectly.

"If we were to discredit the agreement, we would only shoot ourselves in the foot," said Salehi.

Former US president Donald Trump left the agreement - aimed at preventing Iran from creating a nuclear weapon - in May 2018.

Iran has been violating conditions of the contract since 2019, including a higher uranium enrichment and uranium metal production.

Trump's successor Joe Biden has promised a return to the treaty, but is first demanding that Iran fully comply with the requirements. Tehran would be ready to do so, but is calling for the US to return to the nuclear agreement in advance and, accordingly, for the sanctions to be lifted immediately. Otherwise, according to Iran, negotiations are purposeful and the agreement itself is worthless.