Stalled talks between Iran and world powers to reinstate a 2015 nuclear deal will resume "soon", the European Union's foreign policy chief Josep Borrell said on Thursday, while Tehran said it was evaluating the previous rounds of negotiations.

Speaking at a news conference in the Qatari capital Doha, Borrell was referring to indirect talks between Tehran and Washington in Vienna that began in April and were adjourned two days after hard-line cleric Ephraim Raisin won Iran’s presidential election in June.

Borrell, in comments translated into Arabic by Al Jazeera television, said he believed the negotiations aimed at bringing back Tehran and Washington into full compliance with the agreement will resume "within an acceptable period of time".

Western powers have urged Iran to return to negotiations and said time is running out as Tehran's nuclear program is advancing well beyond the limits set by the deal.

Tehran says its nuclear steps are reversible if Washington lifts all sanctions. Iranian and Western officials have said many issues remain to be resolved before the accord can be revived.

Echoing Iran's official stance, Iran's foreign ministry spokesman told Le Monde newspaper that "Iran has reached the conclusion that we certainly will return to the nuclear talks" in Vienna.

Saeed Khatibzadeh added that Iran would not "waste an hour before returning to Vienna talks once a re-evaluation of the sixth round of the nuclear talks" is completed by Raisi's government.

"The Biden administration should finally make a decision: either it wants to preserve Trump's legacy or it wants to build Biden's. This is a purely political decision," said Khatibzadeh, adding that "We don't have a lot of time ahead of us".